A material with a high electron mobility is like a highway without traffic. Any electrons that flow into the material experience a commuter’s dream, breezing through without any obstacles or congestion to slow or scatter them off their path.

The higher a material’s electron mobility, the more efficient its electrical conductivity, and the less energy is lost or wasted as electrons zip through. Advanced materials that exhibit high electron mobility will be essential for more efficient and sustainable electronic devices that can do more work with less power.

Now, physicists at MIT, the Army Research Lab, and elsewhere have achieved a record-setting level of electron mobility in a thin film of ternary tetradymite — a class of mineral that is naturally found in deep hydrothermal deposits of gold and quartz.

For this study, the scientists grew pure, ultrathin films of the material, in a way that minimized defects in its crystalline structure. They found that this nearly perfect film — much thinner than a human hair — exhibits the highest electron mobility in its class.

The team was able to estimate the material’s electron mobility by detecting quantum oscillations when electric current passes through. These oscillations are a signature of the quantum mechanical behavior of electrons in a material. The researchers detected a particular rhythm of oscillations that is characteristic of high electron mobility — higher than any ternary thin films of this class to date.

“Before, what people had achieved in terms of electron mobility in these systems was like traffic on a road under construction — you’re backed up, you can’t drive, it’s dusty, and it’s a mess,” says Jagadeesh Moodera, a senior research scientist in MIT’s Department of Physics. “In this newly optimized material, it’s like driving on the Mass Pike with no traffic.”

The team’s results, which appear today in the journal Materials Today Physics, point to ternary tetradymite thin films as a promising material for future electronics, such as wearable thermoelectric devices that efficiently convert waste heat into electricity. (Tetradymites are the active materials that cause the cooling effect in commercial thermoelectric coolers.) The material could also be the basis for spintronic devices, which process information using an electron’s spin, using far less power than conventional silicon-based devices.

The study also uses quantum oscillations as a highly effective tool for measuring a material’s electronic performance.

“We are using this oscillation as a rapid test kit,” says study author Hang Chi, a former research scientist at MIT who is now at the University of Ottawa. “By studying this delicate quantum dance of electrons, scientists can start to understand and identify new materials for the next generation of technologies that will power our world.”

Chi and Moodera’s co-authors include Patrick Taylor, formerly of MIT Lincoln Laboratory, along with Owen Vail and Harry Hier of the Army Research Lab, and Brandi Wooten and Joseph Heremans of Ohio State University.

Beam down

The name “tetradymite” derives from the Greek “tetra” for “four,” and “dymite,” meaning “twin.” Both terms describe the mineral’s crystal structure, which consists of rhombohedral crystals that are “twinned” in groups of four — i.e. they have identical crystal structures that share a side.

Tetradymites comprise combinations of bismuth, antimony tellurium, sulfur, and selenium. In the 1950s, scientists found that tetradymites exhibit semiconducting properties that could be ideal for thermoelectric applications: The mineral in its bulk crystal form was able to passively convert heat into electricity.

Then, in the 1990s, the late Institute Professor Mildred Dresselhaus proposed that the mineral’s thermoelectric properties might be significantly enhanced, not in its bulk form but within its microscopic, nanometer-scale surface, where the interactions of electrons is more pronounced. (Heremans happened to work in Dresselhaus’ group at the time.)

“It became clear that when you look at this material long enough and close enough, new things will happen,” Chi says. “This material was identified as a topological insulator, where scientists could see very interesting phenomena on their surface. But to keep uncovering new things, we have to master the material growth.”

To grow thin films of pure crystal, the researchers employed molecular beam epitaxy — a method by which a beam of molecules is fired at a substrate, typically in a vacuum, and with precisely controlled temperatures. When the molecules deposit on the substrate, they condense and build up slowly, one atomic layer at a time. By controlling the timing and type of molecules deposited, scientists can grow ultrathin crystal films in exact configurations, with few if any defects.

“Normally, bismuth and tellurium can interchange their position, which creates defects in the crystal,” co-author Taylor explains. “The system we used to grow these films came down with me from MIT Lincoln Laboratory, where we use high purity materials to minimize impurities to undetectable limits. It is the perfect tool to explore this research.”

Free flow

The team grew thin films of ternary tetradymite, each about 100 nanometers thin. They then tested the film’s electronic properties by looking for Shubnikov-de Haas quantum oscillations — a phenomenon that was discovered by physicists Lev Shubnikov and Wander de Haas, who found that a material’s electrical conductivity can oscillate when exposed to a strong magnetic field at low temperatures. This effect occurs because the material’s electrons fill up specific energy levels that shift as the magnetic field changes.

Such quantum oscillations could serve as a signature of a material’s electronic structure, and the ways in which electrons behave and interact. Most notably for the MIT team, the oscillations could determine a material’s electron mobility: If oscillations exist, it must mean that the material’s electrical resistance is able to change, and by inference, electrons can be mobile, and made to easily flow.

The team looked for signs of quantum oscillations in their new films, by first exposing them to ultracold temperatures and a strong magnetic field, then running an electric current through the film and measuring the voltage along its path, as they tuned the magnetic field up and down.

“It turns out, to our great joy and excitement, that the material’s electrical resistance oscillates,” Chi says. “Immediately, that tells you that this has very high electron mobility.”

Specifically, the team estimates that the ternary tetradymite thin film exhibits an electron mobility of 10,000 cm²/V-s — the highest mobility of any ternary tetradymite film yet measured. The team suspects that the film’s record mobility has something to do with its low defects and impurities, which they were able to minimize with their precise growth strategies. The fewer a material’s defects, the fewer obstacles an electron encounters, and the more freely it can flow.

“This is showing it’s possible to go a giant step further, when properly controlling these complex systems,” Moodera says. “This tells us we’re in the right direction, and we have the right system to proceed further, to keep perfecting this material down to even much thinner films and proximity coupling for use in future spintronics and wearable thermoelectric devices.”

This research was supported in part by the Army Research Office, National Science Foundation, Office of Naval Research, Canada Research Chairs Program and Natural Sciences and Engineering Research Council of Canada.

MIT faculty members Nancy Kanwisher, Robert Langer, and Sara Seager are among eight researchers worldwide to receive this year’s Kavli Prizes.

A partnership among the Norwegian Academy of Science and Letters, the Norwegian Ministry of Education and Research, and the Kavli Foundation, the Kavli Prizes are awarded every two years to “honor scientists for breakthroughs in astrophysics, nanoscience and neuroscience that transform our understanding of the big, the small and the complex.” The laureates in each field will share $1 million.

Understanding recognition of faces

Nancy Kanwisher, the Walter A Rosenblith Professor of Brain and Cognitive Sciences and McGovern Institute for Brain Research investigator, has been awarded the 2024 Kavli Prize in Neuroscience with Doris Tsao, professor in the Department of Molecular and Cell Biology at the University of California at Berkeley, and Winrich Freiwald, the Denise A. and Eugene W. Chinery Professor at the Rockefeller University.

Kanwisher, Tsao, and Freiwald discovered a specialized system within the brain to recognize faces. Their discoveries have provided basic principles of neural organization and made the starting point for further research on how the processing of visual information is integrated with other cognitive functions.

Kanwisher was the first to prove that a specific area in the human neocortex is dedicated to recognizing faces, now called the fusiform face area. Using functional magnetic resonance imaging, she found individual differences in the location of this area and devised an analysis technique to effectively localize specialized functional regions in the brain. This technique is now widely used and applied to domains beyond the face recognition system. 

Integrating nanomaterials for biomedical advances

Robert Langer, the David H. Koch Institute Professor, has been awarded the 2024 Kavli Prize in Nanoscience with Paul Alivisatos, president of the University of Chicago and John D. MacArthur Distinguished Service Professor in the Department of Chemistry, and Chad Mirkin, professor of chemistry at Northwestern University.

Langer, Alivisatos, and Mirkin each revolutionized the field of nanomedicine by demonstrating how engineering at the nano scale can advance biomedical research and application. Their discoveries contributed foundationally to the development of therapeutics, vaccines, bioimaging, and diagnostics.

Langer was the first to develop nanoengineered materials that enabled the controlled release, or regular flow, of drug molecules. This capability has had an immense impact for the treatment of a range of diseases, such as aggressive brain cancer, prostate cancer, and schizophrenia. His work also showed that tiny particles, containing protein antigens, can be used in vaccination, and was instrumental in the development of the delivery of messenger RNA vaccines. 

Searching for life beyond Earth

Sara Seager, the Class of 1941 Professor of Planetary Sciences in the Department of Earth, Atmospheric and Planetary Sciences and a professor in the departments of Physics and of Aeronautics and Astronautics, has been awarded the 2024 Kavli Prize in Astrophysics along with David Charbonneau, the Fred Kavli Professor of Astrophysics at Harvard University.

Seager and Charbonneau are recognized for discoveries of exoplanets and the characterization of their atmospheres. They pioneered methods for the detection of atomic species in planetary atmospheres and the measurement of their thermal infrared emission, setting the stage for finding the molecular fingerprints of atmospheres around both giant and rocky planets. Their contributions have been key to the enormous progress seen in the last 20 years in the exploration of myriad exoplanets. 

Kanwisher, Langer, and Seager bring the number of all-time MIT faculty recipients of the Kavli Prize to eight. Prior winners include Rainer Weiss in astrophysics (2016), Alan Guth in astrophysics (2014), Mildred Dresselhaus in nanoscience (2012), Ann Graybiel in neuroscience (2012), and Jane Luu in astrophysics (2012).

MIT physicists and colleagues have created a five-lane superhighway for electrons that could allow ultra-efficient electronics and more. 

The work, reported in the May 10 issue of Science, is one of several important discoveries by the same team over the past year involving a material that is a unique form of graphene.

“This discovery has direct implications for low-power electronic devices because no energy is lost during the propagation of electrons, which is not the case in regular materials where the electrons are scattered,” says Long Ju, an assistant professor in the Department of Physics and corresponding author of the Science paper.

The phenomenon is akin to cars traveling down an open turnpike as opposed to those moving through neighborhoods. The neighborhood cars can be stopped or slowed by other drivers making abrupt stops or U-turns that disrupt an otherwise smooth commute.

A new material

The material behind this work, known as rhombohedral pentalayer graphene, was discovered two years ago by physicists led by Ju. “We found a goldmine, and every scoop is revealing something new,” says Ju, who is also affiliated with MIT’s Materials Research Laboratory.

In a Nature Nanotechnology paper last October, Ju and colleagues reported the discovery of three important properties arising from rhombohedral graphene. For example, they showed that it could be topological, or allow the unimpeded movement of electrons around the edge of the material but not through the middle. That resulted in a superhighway, but required the application of a large magnetic field some tens of thousands times stronger than the Earth’s magnetic field.

In the current work, the team reports creating the superhighway without any magnetic field.

Tonghang Han, an MIT graduate student in physics, is a co-first author of the paper. “We are not the first to discover this general phenomenon, but we did so in a very different system. And compared to previous systems, ours is simpler and also supports more electron channels.” Explains Ju, “other materials can only support one lane of traffic on the edge of the material. We suddenly bumped it up to five.”

Additional co-first authors of the paper who contributed equally to the work are Zhengguang Lu and Yuxuan Yao. Lu is a postdoc in the Materials Research Laboratory. Yao conducted the work as a visiting undergraduate student from Tsinghua University. Other authors are MIT professor of physics Liang Fu; Jixiang Yang and Junseok Seo, both MIT graduate students in physics; Chiho Yoon and Fan Zhang of the University of Texas at Dallas; and Kenji Watanabe and Takashi Taniguchi of the National Institute for Materials Science in Japan.

How it works

Graphite, the primary component of pencil lead, is composed of many layers of graphene, a single layer of carbon atoms arranged in hexagons resembling a honeycomb structure. Rhombohedral graphene is composed of five layers of graphene stacked in a specific overlapping order.

Ju and colleagues isolated rhombohedral graphene thanks to a novel microscope Ju built at MIT in 2021 that can quickly and relatively inexpensively determine a variety of important characteristics of a material at the nanoscale. Pentalayer rhombohedral stacked graphene is only a few billionths of a meter thick.

In the current work, the team tinkered with the original system, adding a layer of tungsten disulfide (WS₂). “The interaction between the WS₂ and the pentalayer rhombohedral graphene resulted in this five-lane superhighway that operates at zero magnetic field,” says Ju.

Comparison to superconductivity

The phenomenon that the Ju group discovered in rhombohedral graphene that allows electrons to travel with no resistance at zero magnetic field is known as the quantum anomalous Hall effect. Most people are more familiar with superconductivity, a completely different phenomenon that does the same thing but happens in very different materials.

Ju notes that although superconductors were discovered in the 1910s, it took some 100 years of research to coax the system to work at the higher temperatures necessary for applications. “And the world record is still well below room temperature,” he notes.

Similarly, the rhombohedral graphene superhighway currently operates at about 2 kelvins, or -456 degrees Fahrenheit. “It will take a lot of effort to elevate the temperature, but as physicists, our job is to provide the insight; a different way for realizing this [phenomenon],” Ju says.

Very exciting

The discoveries involving rhombohedral graphene came as a result of painstaking research that wasn’t guaranteed to work. “We tried many recipes over many months,” says Han, “so it was very exciting when we cooled the system to a very low temperature and [a five-lane superhighway operating at zero magnetic field] just popped out.”

Says Ju, “it’s very exciting to be the first to discover a phenomenon in a new system, especially in a material that we uncovered.”

This work was supported by a Sloan Fellowship; the U.S. National Science Foundation; the U.S. Office of the Under Secretary of Defense for Research and Engineering; the Japan Society for the Promotion of Science KAKENHI; and the World Premier International Research Initiative of Japan.

Physics graduate student Jeong Min (Jane) Park is among the 32 exceptional early-career scientists worldwide chosen to receive the prestigious 2024 Schmidt Science Fellows award.  

As a 2024 Schmidt Science Fellow, Park’s postdoctoral work will seek to directly detect phases that could host new particles by employing an instrument that can visualize subatomic-scale phenomena.  

With her advisor, Pablo Jarillo-Herrero, the Cecil and Ida Green Professor of Physics, Park’s research at MIT focuses on discovering novel quantum phases of matter.

“When there are many electrons in a material, their interactions can lead to collective behaviors that are not expected from individual particles, known as emergent phenomena,” explains Park. “One example is superconductivity, where interacting electrons combine together as a pair at low temperatures to conduct electricity without energy loss.”

During her PhD studies, she has investigated novel types of superconductivity by designing new materials with targeted interactions and topology. In particular, she used graphene, atomically thin two-dimensional layers of graphite, the same material as pencil lead, and turned it into a “magic” material. This so-called magic-angle twisted trilayer graphene provided an extraordinarily strong form of superconductivity that is robust under high magnetic fields. Later, she found a whole “magic family” of these materials, elucidating the key mechanisms behind superconductivity and interaction-driven phenomena. These results have provided a new platform to study emergent phenomena in two dimensions, which can lead to innovations in electronics and quantum technology.

Park says she is looking forward to her postdoctoral studies with Princeton University physics professor Ali Yazdani's lab.

“I’m excited about the idea of discovering and studying new quantum phenomena that could further the understanding of fundamental physics,” says Park. “Having explored interaction-driven phenomena through the design of new materials, I’m now aiming to broaden my perspective and expertise to address a different kind of question, by combining my background in material design with the sophisticated local-scale measurements that I will adopt during my postdoc.”

She explains that elementary particles are classified as either bosons or fermions, with contrasting behaviors upon interchanging two identical particles, referred to as exchange statistics; bosons remain unchanged, while fermions acquire a minus sign in their quantum wavefunction.

Theories predict the existence of fundamentally different particles known as non-abelian anyons, whose wavefunctions braid upon particle exchange. Such a braiding process can be used to encode and store information, potentially opening the door to fault-tolerant quantum computing in the future.

Since 2018, this prestigious postdoctoral program has sought to break down silos among scientific fields to solve the world’s biggest challenges and support future leaders in STEM.

Schmidt Science Fellows, an initiative of Schmidt Sciences, delivered in partnership with the Rhodes Trust, identifies, develops, and amplifies the next generation of science leaders, by building a community of scientists and supporters of interdisciplinary science and leveraging this network to drive sector-wide change. The 2024 fellows consist of 17 nationalities across North America, Europe, and Asia.   

Nominated candidates undergo a rigorous selection process that includes a paper-based academic review with panels of experts in their home disciplines and final interviews with panels, including senior representatives from across many scientific disciplines and different business sectors.  

John Joannopoulos, an innovator and mentor in the fields of theoretical condensed matter physics and nanophotonics, has been named the recipient of the 2024-2025 James R. Killian Jr. Faculty Achievement Award.

Joannopoulos is the Francis Wright Davis Professor of Physics and director of MIT’s Institute for Soldier Nanotechnologies. He has been a member of the MIT faculty for 50 years.

“Professor Joannopoulos’s profound and lasting impact on the field of theoretical condensed matter physics finds its roots in his pioneering work in harnessing ab initio physics to elucidate the behavior of materials at the atomic level,” states the award citation, which was announced at today’s faculty meeting by Roger White, chair of the Killian Award Selection Committee and professor of philosophy at MIT. “His seminal research in the development of photonic crystals has revolutionized understanding of light-matter interactions, laying the groundwork for transformative advancements in diverse fields ranging from telecommunications to biomedical engineering.”

The award also honors Joannopoulos’ service as a “legendary mentor to generations of students, inspiring them to achieve excellence in science while at the same time facilitating the practical benefit to society through entrepreneurship.”

The Killian Award was established in 1971 to recognize outstanding professional contributions by MIT faculty members. It is the highest honor that the faculty can give to one of its members.

“I have to tell you, it was a complete and utter surprise,” Joannopoulos told MIT News shortly after he received word of the award. “I didn’t expect it at all, and was extremely flattered, honored, and moved by it, frankly.”

Joannopoulous has spent his entire professional career at MIT. He came to the Institute in 1974, directly after receiving his PhD in physics at the University of California at Berkeley, where he also earned his bachelor’s degree. Starting out as an assistant professor in MIT’s Department of Physics, he quickly set up a research program focused on theoretical condensed matter physics.

Over the first half of his MIT career, Joannopoulos worked to elucidate the fundamental nature of the electronic, vibrational, and optical structure of crystalline and amorphous bulk solids, their surfaces, interfaces, and defects. He and his students developed numerous theoretical methods to enable tractable and accurate calculations of these complex systems.

In the 1990s, his work with microscopic material systems expanded to a new class of materials, called photonic crystals — materials that could be engineered at the micro- and nanoscale to manipulate light in ways that impart surprising and exotic optical qualities to the material as a whole.

“I saw that you could create photonic crystals with defects that can affect the properties of photons, in much the same way that defects in a semiconductor affect the properties of electrons,” Joannopoulos says. “So I started working in this area to try and explore what anomalous light phenomena can we discover using this approach?”

Among his various breakthroughs in the field was the realization of a “perfect dielectric mirror” — a multilayered optical device that reflects light from all angles as normal metallic mirrors do, and that can also be tuned to reflect and trap light at specific frequencies. He and his colleagues saw potential for the mirror to be made into a hollow fiber that could serve as a highly effective optical conduit, for use in a wide range of applications. To further advance the technology, he and his colleagues launched a startup, which has since developed the technology into a flexible, fiber-optic “surgical scalpel.”

Throughout his career, Joannopoulos has helped to launch numerous startups and photonics-based technologies.

“His ability to bridge the gap between academia and industry has not only advanced scientific knowledge but also led to the creation of dozens of new companies, thousands of jobs, and groundbreaking products that continue to benefit society to this day,” the award citation states.

In 2006, Joannopoulos accepted the position as director of MIT’s Institute for Soldier Nanotechnologies (ISN), a collaboration between MIT researchers, industry partners, and military defense experts, who seek innovations to protect and enhance soldiers’ survivability in the field. In his role as ISN head, Joannopoulos has worked across MIT, making connections and supporting new projects with researchers specializing in fields far from his own.

“I get a chance to explore and learn fascinating new things,” says Joannopoulos, who is currently overseeing projects related to hyperspectral imaging, smart and responsive fabrics, and nanodrug delivery. “I love that aspect of really getting to understand what people in other fields are doing. And they’re doing great work across many, many different fields.”

Throughout his career at MIT, Joannopoulos has been especially inspired and motivated by his students, many of whom have gone on to found companies, lead top academic and research institutions, and make significant contributions to their respective fields, including one student who was awarded the Nobel Prize in Physics in 1998.

“One’s proudest moments are the successes of one’s students, and in that regard, I’ve been extremely lucky to have had truly exceptional students over the years,” Joannopolous says.

His many contributions to academia and industry have earned Joannopoulos numerous honors and awards, including his election to both the National Academy of Sciences and the American Academy of Arts and Sciences. He is also a fellow of both the American Physical Society and the American Association for the Advancement of Science.

“The Selection Committee is delighted to have this opportunity to honor Professor John Joannopoulos: a visionary scientist, a beloved mentor, a great believer in the goodness of people, and a leader whose contributions to MIT and the broader scientific community are immeasurable,” the award citation concludes.

Proximity is key for many quantum phenomena, as interactions between atoms are stronger when the particles are close. In many quantum simulators, scientists arrange atoms as close together as possible to explore exotic states of matter and build new quantum materials.

They typically do this by cooling the atoms to a stand-still, then using laser light to position the particles as close as 500 nanometers apart — a limit that is set by the wavelength of light. Now, MIT physicists have developed a technique that allows them to arrange atoms in much closer proximity, down to a mere 50 nanometers. For context, a red blood cell is about 1,000 nanometers wide.

The physicists demonstrated the new approach in experiments with dysprosium, which is the most magnetic atom in nature. They used the new approach to manipulate two layers of dysprosium atoms, and positioned the layers precisely 50 nanometers apart. At this extreme proximity, the magnetic interactions were 1,000 times stronger than if the layers were separated by 500 nanometers.

What’s more, the scientists were able to measure two new effects caused by the atoms’ proximity. Their enhanced magnetic forces caused “thermalization,” or the transfer of heat from one layer to another, as well as synchronized oscillations between layers. These effects petered out as the layers were spaced farther apart.

“We have gone from positioning atoms from 500 nanometers to 50 nanometers apart, and there is a lot you can do with this,” says Wolfgang Ketterle, the John D. MacArthur Professor of Physics at MIT. “At 50 nanometers, the behavior of atoms is so much different that we’re really entering a new regime here.”

Ketterle and his colleagues say the new approach can be applied to many other atoms to study quantum phenomena. For their part, the group plans to use the technique to manipulate atoms into configurations that could generate the first purely magnetic quantum gate — a key building block for a new type of quantum computer.

The team has published their results today in the journal Science. The study’s co-authors include lead author and physics graduate student Li Du, along with Pierre Barral, Michael Cantara, Julius de Hond, and Yu-Kun Lu — all members of the MIT-Harvard Center for Ultracold Atoms, the Department of Physics, and the Research Laboratory of Electronics at MIT.

Peaks and valleys

To manipulate and arrange atoms, physicists typically first cool a cloud of atoms to temperatures approaching absolute zero, then use a system of laser beams to corral the atoms into an optical trap.

Laser light is an electromagnetic wave with a specific wavelength (the distance between maxima of the electric field) and frequency. The wavelength limits the smallest pattern into which light can be shaped to typically 500 nanometers, the so-called optical resolution limit. Since atoms are attracted by laser light of certain frequencies, atoms will be positioned at the points of peak laser intensity. For this reason, existing techniques have been limited in how close they can position atomic particles, and could not be used to explore phenomena that happen at much shorter distances.

“Conventional techniques stop at 500 nanometers, limited not by the atoms but by the wavelength of light,” Ketterle explains. “We have found now a new trick with light where we can break through that limit.”

The team’s new approach, like current techniques, starts by cooling a cloud of atoms — in this case, to about 1 microkelvin, just a hair above absolute zero — at which point, the atoms come to a near-standstill. Physicists can then use lasers to move the frozen particles into desired configurations.

Then, Du and his collaborators worked with two laser beams, each with a different frequency, or color, and circular polarization, or direction of the laser’s electric field. When the two beams travel through a super-cooled cloud of atoms, the atoms can orient their spin in opposite directions, following either of the two lasers’ polarization. The result is that the beams produce two groups of the same atoms, only with opposite spins.

Each laser beam formed a standing wave, a periodic pattern of electric field intensity with a spatial period of 500 nanometers. Due to their different polarizations, each standing wave attracted and corralled one of two groups of atoms, depending on their spin. The lasers could be overlaid and tuned such that the distance between their respective peaks is as small as 50 nanometers, meaning that the atoms gravitating to each respective laser’s peaks would be separated by the same 50 nanometers.

But in order for this to happen, the lasers would have to be extremely stable and immune to all external noise, such as from shaking or even breathing on the experiment. The team realized they could stabilize both lasers by directing them through an optical fiber, which served to lock the light beams in place in relation to each other.

“The idea of sending both beams through the optical fiber meant the whole machine could shake violently, but the two laser beams stayed absolutely stable with respect to each others,” Du says.

Magnetic forces at close range

As a first test of their new technique, the team used atoms of dysprosium — a rare-earth metal that is one of the strongest magnetic elements in the periodic table, particularly at ultracold temperatures. However, at the scale of atoms, the element’s magnetic interactions are relatively weak at distances of even 500 nanometers. As with common refrigerator magnets, the magnetic attraction between atoms increases with proximity, and the scientists suspected that if their new technique could space dysprosium atoms as close as 50 nanometers apart, they might observe the emergence of otherwise weak interactions between the magnetic atoms.

“We could suddenly have magnetic interactions, which used to be almost neglible but now are really strong,” Ketterle says.

The team applied their technique to dysprosium, first super-cooling the atoms, then passing two lasers through to split the atoms into two spin groups, or layers. They then directed the lasers through an optical fiber to stabilize them, and found that indeed, the two layers of dysprosium atoms gravitated to their respective laser peaks, which in effect separated the layers of atoms by 50 nanometers — the closest distance that any ultracold atom experiment has been able to achieve.

At this extremely close proximity, the atoms’ natural magnetic interactions were significantly enhanced, and were 1,000 times stronger than if they were positioned 500 nanometers apart. The team observed that these interactions resulted in two novel quantum phenomena: collective oscillation, in which one layer’s vibrations caused the other layer to vibrate in sync; and thermalization, in which one layer transferred heat to the other, purely through magnetic fluctuations in the atoms.

“Until now, heat between atoms could only by exchanged when they were in the same physical space and could collide,” Du notes. “Now we have seen atomic layers, separated by vacuum, and they exchange heat via fluctuating magnetic fields.”

The team’s results introduce a new technique that can be used to position many types of atom in close proximity. They also show that atoms, placed close enough together, can exhibit interesting quantum phenomena, that could be harnessed to build new quantum materials, and potentially, magnetically-driven atomic systems for quantum computers.

“We are really bringing super-resolution methods to the field, and it will become a general tool for doing quantum simulations,” Ketterle says. “There are many variants possible, which we are working on.”

This research was funded, in part, by the National Science Foundation and the Department of Defense.

Neutrons are subatomic particles that have no electric charge, unlike protons and electrons. That means that while the electromagnetic force is responsible for most of the interactions between radiation and materials, neutrons are essentially immune to that force.

Instead, neutrons are held together inside an atom’s nucleus solely by something called the strong force, one of the four fundamental forces of nature. As its name implies, the force is indeed very strong, but only at very close range — it drops off so rapidly as to be negligible beyond 1/10,000 the size of an atom. But now, researchers at MIT have found that neutrons can actually be made to cling to particles called quantum dots, which are made up of tens of thousands of atomic nuclei, held there just by the strong force.

The new finding may lead to useful new tools for probing the basic properties of materials at the quantum level, including those arising from the strong force, as well as exploring new kinds of quantum information processing devices. The work is reported this week in the journal ACS Nano, in a paper by MIT graduate students Hao Tang and Guoqing Wang and MIT professors Ju Li and Paola Cappellaro of the Department of Nuclear Science and Engineering.

Neutrons are widely used to probe material properties using a method called neutron scattering, in which a beam of neutrons is focused on a sample, and the neutrons that bounce off the material’s atoms can be detected to reveal the material’s internal structure and dynamics.

But until this new work, nobody thought that these neutrons might actually stick to the materials they were probing. “The fact that [the neutrons] can be trapped by the materials, nobody seems to know about that,” says Li, who is also a professor of materials science and engineering. “We were surprised that this exists, and that nobody had talked about it before, among the experts we had checked with,” he says.

The reason this new finding is so surprising, Li explains, is because neutrons don’t interact with electromagnetic forces. Of the four fundamental forces, gravity and the weak force “are generally not important for materials,” he says. “Pretty much everything is electromagnetic interaction, but in this case, since the neutron doesn’t have a charge, the interaction here is through the strong interaction, and we know that is very short-range. It is effective at a range of 10 to the minus 15 power,” or one quadrillionth, of a meter.

“It’s very small, but it’s very intense,” he says of this force that holds the nuclei of atoms together. “But what’s interesting is we’ve got these many thousands of nuclei in this neutronic quantum dot, and that’s able to stabilize these bound states, which have much more diffuse wavefunctions at tens of nanometers [billionths of a meter].  These neutronic bound states in a quantum dot are actually quite akin to Thomson’s plum pudding model of an atom, after his discovery of the electron.”

It was so unexpected, Li calls it “a pretty crazy solution to a quantum mechanical problem.” The team calls the newly discovered state an artificial “neutronic molecule.”

These neutronic molecules are made from quantum dots, which are tiny crystalline particles, collections of atoms so small that their properties are governed more by the exact size and shape of the particles than by their composition. The discovery and controlled production of quantum dots were the subject of the 2023 Nobel Prize in Chemistry, awarded to MIT Professor Moungi Bawendi and two others.

“In conventional quantum dots, an electron is trapped by the electromagnetic potential created by a macroscopic number of atoms, thus its wavefunction extends to about 10 nanometers, much larger than a typical atomic radius,” says Cappellaro. “Similarly, in these nucleonic quantum dots, a single neutron can be trapped by a nanocrystal, with a size well beyond the range of the nuclear force, and display similar quantized energies.” While these energy jumps give quantum dots their colors, the neutronic quantum dots could be used for storing quantum information.

This work is based on theoretical calculations and computational simulations. “We did it analytically in two different ways, and eventually also verified it numerically,” Li says. Although the effect had never been described before, he says, in principle there’s no reason it couldn’t have been found much sooner: “Conceptually, people should have already thought about it,” he says, but as far as the team has been able to determine, nobody did.

Part of the difficulty in doing the computations is the very different scales involved: The binding energy of a neutron to the quantum dots they were attaching to is about one-trillionth that of previously known conditions where the neutron is bound to a small group of nucleons. For this work, the team used an analytical tool called Green’s function to demonstrate that the strong force was sufficient to capture neutrons with a quantum dot with a minimum radius of 13 nanometers.

Then, the researchers did detailed simulations of specific cases, such as the use of a lithium hydride nanocrystal, a material being studied as a possible storage medium for hydrogen. They showed that the binding energy of the neutrons to the nanocrystal is dependent on the exact dimensions and shape of the crystal, as well as the nuclear spin polarizations of the nuclei compared to that of the neutron. They also calculated similar effects for thin films and wires of the material as opposed to particles.

But Li says that actually creating such neutronic molecules in the lab, which among other things requires specialized equipment to maintain temperatures in the range of a few thousandths of a Kelvin above absolute zero, is something that other researchers with the appropriate expertise will have to undertake.

Li notes that “artificial atoms” made up of assemblages of atoms that share properties and can behave in many ways like a single atom have been used to probe many properties of real atoms. Similarly, he says, these artificial molecules provide “an interesting model system” that might be used to study “interesting quantum mechanical problems that one can think about,” such as whether these neutronic molecules will have a shell structure that mimics the electron shell structure of atoms.

“One possible application,” he says, “is maybe we can precisely control the neutron state. By changing the way the quantum dot oscillates, maybe we can shoot the neutron off in a particular direction.” Neutrons are powerful tools for such things as triggering both fission and fusion reactions, but so far it has been difficult to control individual neutrons. These new bound states could provide much greater degrees of control over individual neutrons, which could play a role in the development of new quantum information systems, he says.

“One idea is to use it to manipulate the neutron, and then the neutron will be able to affect other nuclear spins,” Li says. In that sense, he says, the neutronic molecule could serve as a mediator between the nuclear spins of separate nuclei — and this nuclear spin is a property that is already being used as a basic storage unit, or qubit, in developing quantum computer systems.

“The nuclear spin is like a stationary qubit, and the neutron is like a flying qubit,” he says. “That’s one potential application.” He adds that this is “quite different from electromagnetics-based quantum information processing, which is so far the dominant paradigm. So, regardless of whether it’s superconducting qubits or it’s trapped ions or nitrogen vacancy centers, most of these are based on electromagnetic interactions.” In this new system, instead, “we have neutrons and nuclear spin. We’re just starting to explore what we can do with it now.”

Another possible application, he says, is for a kind of imaging, using neutral activation analysis. “Neutron imaging complements X-ray imaging because neutrons are much more strongly interacting with light elements,” Li says. It can also be used for materials analysis, which can provide information not only about elemental composition but even about the different isotopes of those elements. “A lot of the chemical imaging and spectroscopy doesn’t tell us about the isotopes,” whereas the neutron-based method could do so, he says.

The research was supported by the U.S. Office of Naval Research.

A new set of advanced nanofabrication equipment will make MIT.nano one of the world’s most advanced research facilities in microelectronics and related technologies, unlocking new opportunities for experimentation and widening the path for promising inventions to become impactful new products.

The equipment, provided by Applied Materials, will significantly expand MIT.nano’s nanofabrication capabilities, making them compatible with wafers — thin, round slices of semiconductor material — up to 200 millimeters, or 8 inches, in diameter, a size widely used in industry. The new tools will allow researchers to prototype a vast array of new microelectronic devices using state-of-the-art materials and fabrication processes. At the same time, the 200-millimeter compatibility will support close collaboration with industry and enable innovations to be rapidly adopted by companies and mass produced.

MIT.nano’s leaders say the equipment, which will also be available to scientists outside of MIT, will dramatically enhance their facility’s capabilities, allowing experts in the region to more efficiently explore new approaches in “tough tech” sectors, including advanced electronics, next-generation batteries, renewable energies, optical computing, biological sensing, and a host of other areas — many likely yet to be imagined.

“The toolsets will provide an accelerative boost to our ability to launch new technologies that can then be given to the world at scale,” says MIT.nano Director Vladimir Bulović, who is also the Fariborz Maseeh Professor of Emerging Technology. “MIT.nano is committed to its expansive mission — to build a better world. We provide toolsets and capabilities that, in the hands of brilliant researchers, can effectively move the world forward.”

The announcement comes as part of an agreement between MIT and Applied Materials, Inc. that, together with a grant to MIT from the Northeast Microelectronics Coalition (NEMC) Hub, commits more than $40 million of estimated private and public investment to add advanced nano-fabrication equipment and capabilities at MIT.nano.

“We don’t believe there is another space in the United States that will offer the same kind of versatility, capability, and accessibility, with 8-inch toolsets integrated right next to more fundamental toolsets for research discoveries,” Bulović says. “It will create a seamless path to accelerate the pace of innovation.”

Pushing the boundaries of innovation

Applied Materials is the world’s largest supplier of equipment for manufacturing semiconductors, displays, and other advanced electronics. The company will provide at MIT.nano several state-of-the-art process tools capable of supporting 150- and 200-millimeter wafers and will enhance and upgrade an existing tool owned by MIT. In addition to assisting MIT.nano in the day-to-day operation and maintenance of the equipment, Applied Materials engineers will develop new process capabilities to benefit researchers and students from MIT and beyond.

“This investment will significantly accelerate the pace of innovation and discovery in microelectronics and microsystems,” says Tomás Palacios, director of MIT’s Microsystems Technology Laboratories and the Clarence J. Lebel Professor in Electrical Engineering. “It’s wonderful news for our community, wonderful news for the state, and, in my view, a tremendous step forward toward implementing the national vision for the future of innovation in microelectronics.”

Nanoscale research at universities is traditionally conducted on machines that are less compatible with industry, which makes academic innovations more difficult to turn into impactful, mass-produced products. Jorg Scholvin, associate director for MIT.nano’s shared fabrication facility, says the new machines, when combined with MIT.nano’s existing equipment, represent a step-change improvement in that area: Researchers will be able to take an industry-standard wafer and build their technology on top of it to prove to companies it works on existing devices, or to co-fabricate new ideas in close collaboration with industry partners.

“In the journey from an idea to a fully working device, the ability to begin on a small scale, figure out what you want to do, rapidly debug your designs, and then scale it up to an industry-scale wafer is critical,” Scholvin says. “It means a student can test out their idea on wafer-scale quickly and directly incorporate insights into their project so that their processes are scalable. Providing such proof-of-principle early on will accelerate the idea out of the academic environment, potentially reducing years of added effort. Other tools at MIT.nano can supplement work on the 200-millimeter wafer scale, but the higher throughput and higher precision of the Applied equipment will provide researchers with repeatability and accuracy that is unprecedented for academic research environments. Essentially what you have is a sharper, faster, more precise tool to do your work.”

Scholvin predicts the equipment will lead to exponential growth in research opportunities.

“I think a key benefit of these tools is they allow us to push the boundary of research in a variety of different ways that we can predict today,” Scholvin says. “But then there are also unpredictable benefits, which are hiding in the shadows waiting to be discovered by the creativity of the researchers at MIT. With each new application, more ideas and paths usually come to mind — so that over time, more and more opportunities are discovered.”

Because the equipment is available for use by people outside of the MIT community, including regional researchers, industry partners, nonprofit organizations, and local startups, they will also enable new collaborations.

“The tools themselves will be an incredible meeting place — a place that can, I think, transpose the best of our ideas in a much more effective way than before,” Bulović says. “I’m extremely excited about that.”

Palacios notes that while microelectronics is best known for work making transistors smaller to fit on microprocessors, it’s a vast field that enables virtually all the technology around us, from wireless communications and high-speed internet to energy management, personalized health care, and more.

He says he’s personally excited to use the new machines to do research around power electronics and semiconductors, including exploring promising new materials like gallium nitride, which could dramatically improve the efficiency of electronic devices.

Fulfilling a mission

MIT.nano’s leaders say a key driver of commercialization will be startups, both from MIT and beyond.

“This is not only going to help the MIT research community innovate faster, it’s also going to enable a new wave of entrepreneurship,” Palacios says. “We’re reducing the barriers for students, faculty, and other entrepreneurs to be able to take innovation and get it to market. That fits nicely with MIT’s mission of making the world a better place through technology. I cannot wait to see the amazing new inventions that our colleagues and students will come out with.”

Bulović says the announcement aligns with the mission laid out by MIT’s leaders at MIT.nano’s inception.

"We have the space in MIT.nano to accommodate these tools, we have the capabilities inside MIT.nano to manage their operation, and as a shared and open facility, we have methodologies by which we can welcome anyone from the region to use the tools,” Bulović says. “That is the vision MIT laid out as we were designing MIT.nano, and this announcement helps to fulfill that vision.”

On the morning of April 4, physicists filed into a third-floor meeting room at Harvard University’s Jefferson Laboratory. Word had gotten out that there would be a big announcement from the Dark Energy Spectroscopic Instrument (DESI) collaboration, a group of physicists who are investigating dark energy — a mysterious, repulsive form of energy that permeates the universe. The meeting room at...

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Nearly a century ago, Edwin Hubble discovered that the universe is getting larger. Modern measurements of how fast it is expanding disagree, however, suggesting that our understanding of the laws of physics might be off. Everyone expected the sharp vision of the James Webb Space Telescope to bring the answer into focus. But a long-awaited analysis of the telescope’s observations released late...

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I'm struggling with a wee issue where if my character walks up a slope he slides back down when at rest, and bounces down when running down the slope. I've followed a few videos but none seem to address the issue. I've posted my movement code so far and I'm not opposed to fundamentally changing this, however with the other aspects of my game, the rigid body and collider setup seems to be working quite well. Any ideas?

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Enlarge / The two spacecraft for NASA's ESCAPADE mission at Rocket Lab's factory in Long Beach, California. (credit: Rocket Lab)

Two NASA spacecraft built by Rocket Lab are on the road from California to Florida this weekend to begin preparations for launch on Blue Origin's first New Glenn rocket.

These two science probes must launch between late September and mid-October to take advantage of a planetary alignment between Earth and Mars that only happens once every 26 months. NASA tapped Blue Origin, Jeff Bezos' space company, to launch the Escape and Plasma Acceleration and Dynamics Explorers (ESCAPADE) mission with a $20 million contract.

Last November, the space agency confirmed the $79 million ESCAPADE mission will launch on the inaugural flight of Blue Origin's New Glenn rocket. With this piece of information, the opaque schedule for Blue Origin's long-delayed first New Glenn mission suddenly became more clear.

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A material with a high electron mobility is like a highway without traffic. Any electrons that flow into the material experience a commuter’s dream, breezing through without any obstacles or congestion to slow or scatter them off their path.

The higher a material’s electron mobility, the more efficient its electrical conductivity, and the less energy is lost or wasted as electrons zip through. Advanced materials that exhibit high electron mobility will be essential for more efficient and sustainable electronic devices that can do more work with less power.

Now, physicists at MIT, the Army Research Lab, and elsewhere have achieved a record-setting level of electron mobility in a thin film of ternary tetradymite — a class of mineral that is naturally found in deep hydrothermal deposits of gold and quartz.

For this study, the scientists grew pure, ultrathin films of the material, in a way that minimized defects in its crystalline structure. They found that this nearly perfect film — much thinner than a human hair — exhibits the highest electron mobility in its class.

The team was able to estimate the material’s electron mobility by detecting quantum oscillations when electric current passes through. These oscillations are a signature of the quantum mechanical behavior of electrons in a material. The researchers detected a particular rhythm of oscillations that is characteristic of high electron mobility — higher than any ternary thin films of this class to date.

“Before, what people had achieved in terms of electron mobility in these systems was like traffic on a road under construction — you’re backed up, you can’t drive, it’s dusty, and it’s a mess,” says Jagadeesh Moodera, a senior research scientist in MIT’s Department of Physics. “In this newly optimized material, it’s like driving on the Mass Pike with no traffic.”

The team’s results, which appear today in the journal Materials Today Physics, point to ternary tetradymite thin films as a promising material for future electronics, such as wearable thermoelectric devices that efficiently convert waste heat into electricity. (Tetradymites are the active materials that cause the cooling effect in commercial thermoelectric coolers.) The material could also be the basis for spintronic devices, which process information using an electron’s spin, using far less power than conventional silicon-based devices.

The study also uses quantum oscillations as a highly effective tool for measuring a material’s electronic performance.

“We are using this oscillation as a rapid test kit,” says study author Hang Chi, a former research scientist at MIT who is now at the University of Ottawa. “By studying this delicate quantum dance of electrons, scientists can start to understand and identify new materials for the next generation of technologies that will power our world.”

Chi and Moodera’s co-authors include Patrick Taylor, formerly of MIT Lincoln Laboratory, along with Owen Vail and Harry Hier of the Army Research Lab, and Brandi Wooten and Joseph Heremans of Ohio State University.

Beam down

The name “tetradymite” derives from the Greek “tetra” for “four,” and “dymite,” meaning “twin.” Both terms describe the mineral’s crystal structure, which consists of rhombohedral crystals that are “twinned” in groups of four — i.e. they have identical crystal structures that share a side.

Tetradymites comprise combinations of bismuth, antimony tellurium, sulfur, and selenium. In the 1950s, scientists found that tetradymites exhibit semiconducting properties that could be ideal for thermoelectric applications: The mineral in its bulk crystal form was able to passively convert heat into electricity.

Then, in the 1990s, the late Institute Professor Mildred Dresselhaus proposed that the mineral’s thermoelectric properties might be significantly enhanced, not in its bulk form but within its microscopic, nanometer-scale surface, where the interactions of electrons is more pronounced. (Heremans happened to work in Dresselhaus’ group at the time.)

“It became clear that when you look at this material long enough and close enough, new things will happen,” Chi says. “This material was identified as a topological insulator, where scientists could see very interesting phenomena on their surface. But to keep uncovering new things, we have to master the material growth.”

To grow thin films of pure crystal, the researchers employed molecular beam epitaxy — a method by which a beam of molecules is fired at a substrate, typically in a vacuum, and with precisely controlled temperatures. When the molecules deposit on the substrate, they condense and build up slowly, one atomic layer at a time. By controlling the timing and type of molecules deposited, scientists can grow ultrathin crystal films in exact configurations, with few if any defects.

“Normally, bismuth and tellurium can interchange their position, which creates defects in the crystal,” co-author Taylor explains. “The system we used to grow these films came down with me from MIT Lincoln Laboratory, where we use high purity materials to minimize impurities to undetectable limits. It is the perfect tool to explore this research.”

Free flow

The team grew thin films of ternary tetradymite, each about 100 nanometers thin. They then tested the film’s electronic properties by looking for Shubnikov-de Haas quantum oscillations — a phenomenon that was discovered by physicists Lev Shubnikov and Wander de Haas, who found that a material’s electrical conductivity can oscillate when exposed to a strong magnetic field at low temperatures. This effect occurs because the material’s electrons fill up specific energy levels that shift as the magnetic field changes.

Such quantum oscillations could serve as a signature of a material’s electronic structure, and the ways in which electrons behave and interact. Most notably for the MIT team, the oscillations could determine a material’s electron mobility: If oscillations exist, it must mean that the material’s electrical resistance is able to change, and by inference, electrons can be mobile, and made to easily flow.

The team looked for signs of quantum oscillations in their new films, by first exposing them to ultracold temperatures and a strong magnetic field, then running an electric current through the film and measuring the voltage along its path, as they tuned the magnetic field up and down.

“It turns out, to our great joy and excitement, that the material’s electrical resistance oscillates,” Chi says. “Immediately, that tells you that this has very high electron mobility.”

Specifically, the team estimates that the ternary tetradymite thin film exhibits an electron mobility of 10,000 cm²/V-s — the highest mobility of any ternary tetradymite film yet measured. The team suspects that the film’s record mobility has something to do with its low defects and impurities, which they were able to minimize with their precise growth strategies. The fewer a material’s defects, the fewer obstacles an electron encounters, and the more freely it can flow.

“This is showing it’s possible to go a giant step further, when properly controlling these complex systems,” Moodera says. “This tells us we’re in the right direction, and we have the right system to proceed further, to keep perfecting this material down to even much thinner films and proximity coupling for use in future spintronics and wearable thermoelectric devices.”

This research was supported in part by the Army Research Office, National Science Foundation, Office of Naval Research, Canada Research Chairs Program and Natural Sciences and Engineering Research Council of Canada.

MIT faculty members Nancy Kanwisher, Robert Langer, and Sara Seager are among eight researchers worldwide to receive this year’s Kavli Prizes.

A partnership among the Norwegian Academy of Science and Letters, the Norwegian Ministry of Education and Research, and the Kavli Foundation, the Kavli Prizes are awarded every two years to “honor scientists for breakthroughs in astrophysics, nanoscience and neuroscience that transform our understanding of the big, the small and the complex.” The laureates in each field will share $1 million.

Understanding recognition of faces

Nancy Kanwisher, the Walter A Rosenblith Professor of Brain and Cognitive Sciences and McGovern Institute for Brain Research investigator, has been awarded the 2024 Kavli Prize in Neuroscience with Doris Tsao, professor in the Department of Molecular and Cell Biology at the University of California at Berkeley, and Winrich Freiwald, the Denise A. and Eugene W. Chinery Professor at the Rockefeller University.

Kanwisher, Tsao, and Freiwald discovered a specialized system within the brain to recognize faces. Their discoveries have provided basic principles of neural organization and made the starting point for further research on how the processing of visual information is integrated with other cognitive functions.

Kanwisher was the first to prove that a specific area in the human neocortex is dedicated to recognizing faces, now called the fusiform face area. Using functional magnetic resonance imaging, she found individual differences in the location of this area and devised an analysis technique to effectively localize specialized functional regions in the brain. This technique is now widely used and applied to domains beyond the face recognition system. 

Integrating nanomaterials for biomedical advances

Robert Langer, the David H. Koch Institute Professor, has been awarded the 2024 Kavli Prize in Nanoscience with Paul Alivisatos, president of the University of Chicago and John D. MacArthur Distinguished Service Professor in the Department of Chemistry, and Chad Mirkin, professor of chemistry at Northwestern University.

Langer, Alivisatos, and Mirkin each revolutionized the field of nanomedicine by demonstrating how engineering at the nano scale can advance biomedical research and application. Their discoveries contributed foundationally to the development of therapeutics, vaccines, bioimaging, and diagnostics.

Langer was the first to develop nanoengineered materials that enabled the controlled release, or regular flow, of drug molecules. This capability has had an immense impact for the treatment of a range of diseases, such as aggressive brain cancer, prostate cancer, and schizophrenia. His work also showed that tiny particles, containing protein antigens, can be used in vaccination, and was instrumental in the development of the delivery of messenger RNA vaccines. 

Searching for life beyond Earth

Sara Seager, the Class of 1941 Professor of Planetary Sciences in the Department of Earth, Atmospheric and Planetary Sciences and a professor in the departments of Physics and of Aeronautics and Astronautics, has been awarded the 2024 Kavli Prize in Astrophysics along with David Charbonneau, the Fred Kavli Professor of Astrophysics at Harvard University.

Seager and Charbonneau are recognized for discoveries of exoplanets and the characterization of their atmospheres. They pioneered methods for the detection of atomic species in planetary atmospheres and the measurement of their thermal infrared emission, setting the stage for finding the molecular fingerprints of atmospheres around both giant and rocky planets. Their contributions have been key to the enormous progress seen in the last 20 years in the exploration of myriad exoplanets. 

Kanwisher, Langer, and Seager bring the number of all-time MIT faculty recipients of the Kavli Prize to eight. Prior winners include Rainer Weiss in astrophysics (2016), Alan Guth in astrophysics (2014), Mildred Dresselhaus in nanoscience (2012), Ann Graybiel in neuroscience (2012), and Jane Luu in astrophysics (2012).

MIT physicists and colleagues have created a five-lane superhighway for electrons that could allow ultra-efficient electronics and more. 

The work, reported in the May 10 issue of Science, is one of several important discoveries by the same team over the past year involving a material that is a unique form of graphene.

“This discovery has direct implications for low-power electronic devices because no energy is lost during the propagation of electrons, which is not the case in regular materials where the electrons are scattered,” says Long Ju, an assistant professor in the Department of Physics and corresponding author of the Science paper.

The phenomenon is akin to cars traveling down an open turnpike as opposed to those moving through neighborhoods. The neighborhood cars can be stopped or slowed by other drivers making abrupt stops or U-turns that disrupt an otherwise smooth commute.

A new material

The material behind this work, known as rhombohedral pentalayer graphene, was discovered two years ago by physicists led by Ju. “We found a goldmine, and every scoop is revealing something new,” says Ju, who is also affiliated with MIT’s Materials Research Laboratory.

In a Nature Nanotechnology paper last October, Ju and colleagues reported the discovery of three important properties arising from rhombohedral graphene. For example, they showed that it could be topological, or allow the unimpeded movement of electrons around the edge of the material but not through the middle. That resulted in a superhighway, but required the application of a large magnetic field some tens of thousands times stronger than the Earth’s magnetic field.

In the current work, the team reports creating the superhighway without any magnetic field.

Tonghang Han, an MIT graduate student in physics, is a co-first author of the paper. “We are not the first to discover this general phenomenon, but we did so in a very different system. And compared to previous systems, ours is simpler and also supports more electron channels.” Explains Ju, “other materials can only support one lane of traffic on the edge of the material. We suddenly bumped it up to five.”

Additional co-first authors of the paper who contributed equally to the work are Zhengguang Lu and Yuxuan Yao. Lu is a postdoc in the Materials Research Laboratory. Yao conducted the work as a visiting undergraduate student from Tsinghua University. Other authors are MIT professor of physics Liang Fu; Jixiang Yang and Junseok Seo, both MIT graduate students in physics; Chiho Yoon and Fan Zhang of the University of Texas at Dallas; and Kenji Watanabe and Takashi Taniguchi of the National Institute for Materials Science in Japan.

How it works

Graphite, the primary component of pencil lead, is composed of many layers of graphene, a single layer of carbon atoms arranged in hexagons resembling a honeycomb structure. Rhombohedral graphene is composed of five layers of graphene stacked in a specific overlapping order.

Ju and colleagues isolated rhombohedral graphene thanks to a novel microscope Ju built at MIT in 2021 that can quickly and relatively inexpensively determine a variety of important characteristics of a material at the nanoscale. Pentalayer rhombohedral stacked graphene is only a few billionths of a meter thick.

In the current work, the team tinkered with the original system, adding a layer of tungsten disulfide (WS₂). “The interaction between the WS₂ and the pentalayer rhombohedral graphene resulted in this five-lane superhighway that operates at zero magnetic field,” says Ju.

Comparison to superconductivity

The phenomenon that the Ju group discovered in rhombohedral graphene that allows electrons to travel with no resistance at zero magnetic field is known as the quantum anomalous Hall effect. Most people are more familiar with superconductivity, a completely different phenomenon that does the same thing but happens in very different materials.

Ju notes that although superconductors were discovered in the 1910s, it took some 100 years of research to coax the system to work at the higher temperatures necessary for applications. “And the world record is still well below room temperature,” he notes.

Similarly, the rhombohedral graphene superhighway currently operates at about 2 kelvins, or -456 degrees Fahrenheit. “It will take a lot of effort to elevate the temperature, but as physicists, our job is to provide the insight; a different way for realizing this [phenomenon],” Ju says.

Very exciting

The discoveries involving rhombohedral graphene came as a result of painstaking research that wasn’t guaranteed to work. “We tried many recipes over many months,” says Han, “so it was very exciting when we cooled the system to a very low temperature and [a five-lane superhighway operating at zero magnetic field] just popped out.”

Says Ju, “it’s very exciting to be the first to discover a phenomenon in a new system, especially in a material that we uncovered.”

This work was supported by a Sloan Fellowship; the U.S. National Science Foundation; the U.S. Office of the Under Secretary of Defense for Research and Engineering; the Japan Society for the Promotion of Science KAKENHI; and the World Premier International Research Initiative of Japan.

Physics graduate student Jeong Min (Jane) Park is among the 32 exceptional early-career scientists worldwide chosen to receive the prestigious 2024 Schmidt Science Fellows award.  

As a 2024 Schmidt Science Fellow, Park’s postdoctoral work will seek to directly detect phases that could host new particles by employing an instrument that can visualize subatomic-scale phenomena.  

With her advisor, Pablo Jarillo-Herrero, the Cecil and Ida Green Professor of Physics, Park’s research at MIT focuses on discovering novel quantum phases of matter.

“When there are many electrons in a material, their interactions can lead to collective behaviors that are not expected from individual particles, known as emergent phenomena,” explains Park. “One example is superconductivity, where interacting electrons combine together as a pair at low temperatures to conduct electricity without energy loss.”

During her PhD studies, she has investigated novel types of superconductivity by designing new materials with targeted interactions and topology. In particular, she used graphene, atomically thin two-dimensional layers of graphite, the same material as pencil lead, and turned it into a “magic” material. This so-called magic-angle twisted trilayer graphene provided an extraordinarily strong form of superconductivity that is robust under high magnetic fields. Later, she found a whole “magic family” of these materials, elucidating the key mechanisms behind superconductivity and interaction-driven phenomena. These results have provided a new platform to study emergent phenomena in two dimensions, which can lead to innovations in electronics and quantum technology.

Park says she is looking forward to her postdoctoral studies with Princeton University physics professor Ali Yazdani's lab.

“I’m excited about the idea of discovering and studying new quantum phenomena that could further the understanding of fundamental physics,” says Park. “Having explored interaction-driven phenomena through the design of new materials, I’m now aiming to broaden my perspective and expertise to address a different kind of question, by combining my background in material design with the sophisticated local-scale measurements that I will adopt during my postdoc.”

She explains that elementary particles are classified as either bosons or fermions, with contrasting behaviors upon interchanging two identical particles, referred to as exchange statistics; bosons remain unchanged, while fermions acquire a minus sign in their quantum wavefunction.

Theories predict the existence of fundamentally different particles known as non-abelian anyons, whose wavefunctions braid upon particle exchange. Such a braiding process can be used to encode and store information, potentially opening the door to fault-tolerant quantum computing in the future.

Since 2018, this prestigious postdoctoral program has sought to break down silos among scientific fields to solve the world’s biggest challenges and support future leaders in STEM.

Schmidt Science Fellows, an initiative of Schmidt Sciences, delivered in partnership with the Rhodes Trust, identifies, develops, and amplifies the next generation of science leaders, by building a community of scientists and supporters of interdisciplinary science and leveraging this network to drive sector-wide change. The 2024 fellows consist of 17 nationalities across North America, Europe, and Asia.   

Nominated candidates undergo a rigorous selection process that includes a paper-based academic review with panels of experts in their home disciplines and final interviews with panels, including senior representatives from across many scientific disciplines and different business sectors.  

John Joannopoulos, an innovator and mentor in the fields of theoretical condensed matter physics and nanophotonics, has been named the recipient of the 2024-2025 James R. Killian Jr. Faculty Achievement Award.

Joannopoulos is the Francis Wright Davis Professor of Physics and director of MIT’s Institute for Soldier Nanotechnologies. He has been a member of the MIT faculty for 50 years.

“Professor Joannopoulos’s profound and lasting impact on the field of theoretical condensed matter physics finds its roots in his pioneering work in harnessing ab initio physics to elucidate the behavior of materials at the atomic level,” states the award citation, which was announced at today’s faculty meeting by Roger White, chair of the Killian Award Selection Committee and professor of philosophy at MIT. “His seminal research in the development of photonic crystals has revolutionized understanding of light-matter interactions, laying the groundwork for transformative advancements in diverse fields ranging from telecommunications to biomedical engineering.”

The award also honors Joannopoulos’ service as a “legendary mentor to generations of students, inspiring them to achieve excellence in science while at the same time facilitating the practical benefit to society through entrepreneurship.”

The Killian Award was established in 1971 to recognize outstanding professional contributions by MIT faculty members. It is the highest honor that the faculty can give to one of its members.

“I have to tell you, it was a complete and utter surprise,” Joannopoulos told MIT News shortly after he received word of the award. “I didn’t expect it at all, and was extremely flattered, honored, and moved by it, frankly.”

Joannopoulous has spent his entire professional career at MIT. He came to the Institute in 1974, directly after receiving his PhD in physics at the University of California at Berkeley, where he also earned his bachelor’s degree. Starting out as an assistant professor in MIT’s Department of Physics, he quickly set up a research program focused on theoretical condensed matter physics.

Over the first half of his MIT career, Joannopoulos worked to elucidate the fundamental nature of the electronic, vibrational, and optical structure of crystalline and amorphous bulk solids, their surfaces, interfaces, and defects. He and his students developed numerous theoretical methods to enable tractable and accurate calculations of these complex systems.

In the 1990s, his work with microscopic material systems expanded to a new class of materials, called photonic crystals — materials that could be engineered at the micro- and nanoscale to manipulate light in ways that impart surprising and exotic optical qualities to the material as a whole.

“I saw that you could create photonic crystals with defects that can affect the properties of photons, in much the same way that defects in a semiconductor affect the properties of electrons,” Joannopoulos says. “So I started working in this area to try and explore what anomalous light phenomena can we discover using this approach?”

Among his various breakthroughs in the field was the realization of a “perfect dielectric mirror” — a multilayered optical device that reflects light from all angles as normal metallic mirrors do, and that can also be tuned to reflect and trap light at specific frequencies. He and his colleagues saw potential for the mirror to be made into a hollow fiber that could serve as a highly effective optical conduit, for use in a wide range of applications. To further advance the technology, he and his colleagues launched a startup, which has since developed the technology into a flexible, fiber-optic “surgical scalpel.”

Throughout his career, Joannopoulos has helped to launch numerous startups and photonics-based technologies.

“His ability to bridge the gap between academia and industry has not only advanced scientific knowledge but also led to the creation of dozens of new companies, thousands of jobs, and groundbreaking products that continue to benefit society to this day,” the award citation states.

In 2006, Joannopoulos accepted the position as director of MIT’s Institute for Soldier Nanotechnologies (ISN), a collaboration between MIT researchers, industry partners, and military defense experts, who seek innovations to protect and enhance soldiers’ survivability in the field. In his role as ISN head, Joannopoulos has worked across MIT, making connections and supporting new projects with researchers specializing in fields far from his own.

“I get a chance to explore and learn fascinating new things,” says Joannopoulos, who is currently overseeing projects related to hyperspectral imaging, smart and responsive fabrics, and nanodrug delivery. “I love that aspect of really getting to understand what people in other fields are doing. And they’re doing great work across many, many different fields.”

Throughout his career at MIT, Joannopoulos has been especially inspired and motivated by his students, many of whom have gone on to found companies, lead top academic and research institutions, and make significant contributions to their respective fields, including one student who was awarded the Nobel Prize in Physics in 1998.

“One’s proudest moments are the successes of one’s students, and in that regard, I’ve been extremely lucky to have had truly exceptional students over the years,” Joannopolous says.

His many contributions to academia and industry have earned Joannopoulos numerous honors and awards, including his election to both the National Academy of Sciences and the American Academy of Arts and Sciences. He is also a fellow of both the American Physical Society and the American Association for the Advancement of Science.

“The Selection Committee is delighted to have this opportunity to honor Professor John Joannopoulos: a visionary scientist, a beloved mentor, a great believer in the goodness of people, and a leader whose contributions to MIT and the broader scientific community are immeasurable,” the award citation concludes.

Proximity is key for many quantum phenomena, as interactions between atoms are stronger when the particles are close. In many quantum simulators, scientists arrange atoms as close together as possible to explore exotic states of matter and build new quantum materials.

They typically do this by cooling the atoms to a stand-still, then using laser light to position the particles as close as 500 nanometers apart — a limit that is set by the wavelength of light. Now, MIT physicists have developed a technique that allows them to arrange atoms in much closer proximity, down to a mere 50 nanometers. For context, a red blood cell is about 1,000 nanometers wide.

The physicists demonstrated the new approach in experiments with dysprosium, which is the most magnetic atom in nature. They used the new approach to manipulate two layers of dysprosium atoms, and positioned the layers precisely 50 nanometers apart. At this extreme proximity, the magnetic interactions were 1,000 times stronger than if the layers were separated by 500 nanometers.

What’s more, the scientists were able to measure two new effects caused by the atoms’ proximity. Their enhanced magnetic forces caused “thermalization,” or the transfer of heat from one layer to another, as well as synchronized oscillations between layers. These effects petered out as the layers were spaced farther apart.

“We have gone from positioning atoms from 500 nanometers to 50 nanometers apart, and there is a lot you can do with this,” says Wolfgang Ketterle, the John D. MacArthur Professor of Physics at MIT. “At 50 nanometers, the behavior of atoms is so much different that we’re really entering a new regime here.”

Ketterle and his colleagues say the new approach can be applied to many other atoms to study quantum phenomena. For their part, the group plans to use the technique to manipulate atoms into configurations that could generate the first purely magnetic quantum gate — a key building block for a new type of quantum computer.

The team has published their results today in the journal Science. The study’s co-authors include lead author and physics graduate student Li Du, along with Pierre Barral, Michael Cantara, Julius de Hond, and Yu-Kun Lu — all members of the MIT-Harvard Center for Ultracold Atoms, the Department of Physics, and the Research Laboratory of Electronics at MIT.

Peaks and valleys

To manipulate and arrange atoms, physicists typically first cool a cloud of atoms to temperatures approaching absolute zero, then use a system of laser beams to corral the atoms into an optical trap.

Laser light is an electromagnetic wave with a specific wavelength (the distance between maxima of the electric field) and frequency. The wavelength limits the smallest pattern into which light can be shaped to typically 500 nanometers, the so-called optical resolution limit. Since atoms are attracted by laser light of certain frequencies, atoms will be positioned at the points of peak laser intensity. For this reason, existing techniques have been limited in how close they can position atomic particles, and could not be used to explore phenomena that happen at much shorter distances.

“Conventional techniques stop at 500 nanometers, limited not by the atoms but by the wavelength of light,” Ketterle explains. “We have found now a new trick with light where we can break through that limit.”

The team’s new approach, like current techniques, starts by cooling a cloud of atoms — in this case, to about 1 microkelvin, just a hair above absolute zero — at which point, the atoms come to a near-standstill. Physicists can then use lasers to move the frozen particles into desired configurations.

Then, Du and his collaborators worked with two laser beams, each with a different frequency, or color, and circular polarization, or direction of the laser’s electric field. When the two beams travel through a super-cooled cloud of atoms, the atoms can orient their spin in opposite directions, following either of the two lasers’ polarization. The result is that the beams produce two groups of the same atoms, only with opposite spins.

Each laser beam formed a standing wave, a periodic pattern of electric field intensity with a spatial period of 500 nanometers. Due to their different polarizations, each standing wave attracted and corralled one of two groups of atoms, depending on their spin. The lasers could be overlaid and tuned such that the distance between their respective peaks is as small as 50 nanometers, meaning that the atoms gravitating to each respective laser’s peaks would be separated by the same 50 nanometers.

But in order for this to happen, the lasers would have to be extremely stable and immune to all external noise, such as from shaking or even breathing on the experiment. The team realized they could stabilize both lasers by directing them through an optical fiber, which served to lock the light beams in place in relation to each other.

“The idea of sending both beams through the optical fiber meant the whole machine could shake violently, but the two laser beams stayed absolutely stable with respect to each others,” Du says.

Magnetic forces at close range

As a first test of their new technique, the team used atoms of dysprosium — a rare-earth metal that is one of the strongest magnetic elements in the periodic table, particularly at ultracold temperatures. However, at the scale of atoms, the element’s magnetic interactions are relatively weak at distances of even 500 nanometers. As with common refrigerator magnets, the magnetic attraction between atoms increases with proximity, and the scientists suspected that if their new technique could space dysprosium atoms as close as 50 nanometers apart, they might observe the emergence of otherwise weak interactions between the magnetic atoms.

“We could suddenly have magnetic interactions, which used to be almost neglible but now are really strong,” Ketterle says.

The team applied their technique to dysprosium, first super-cooling the atoms, then passing two lasers through to split the atoms into two spin groups, or layers. They then directed the lasers through an optical fiber to stabilize them, and found that indeed, the two layers of dysprosium atoms gravitated to their respective laser peaks, which in effect separated the layers of atoms by 50 nanometers — the closest distance that any ultracold atom experiment has been able to achieve.

At this extremely close proximity, the atoms’ natural magnetic interactions were significantly enhanced, and were 1,000 times stronger than if they were positioned 500 nanometers apart. The team observed that these interactions resulted in two novel quantum phenomena: collective oscillation, in which one layer’s vibrations caused the other layer to vibrate in sync; and thermalization, in which one layer transferred heat to the other, purely through magnetic fluctuations in the atoms.

“Until now, heat between atoms could only by exchanged when they were in the same physical space and could collide,” Du notes. “Now we have seen atomic layers, separated by vacuum, and they exchange heat via fluctuating magnetic fields.”

The team’s results introduce a new technique that can be used to position many types of atom in close proximity. They also show that atoms, placed close enough together, can exhibit interesting quantum phenomena, that could be harnessed to build new quantum materials, and potentially, magnetically-driven atomic systems for quantum computers.

“We are really bringing super-resolution methods to the field, and it will become a general tool for doing quantum simulations,” Ketterle says. “There are many variants possible, which we are working on.”

This research was funded, in part, by the National Science Foundation and the Department of Defense.

Neutrons are subatomic particles that have no electric charge, unlike protons and electrons. That means that while the electromagnetic force is responsible for most of the interactions between radiation and materials, neutrons are essentially immune to that force.

Instead, neutrons are held together inside an atom’s nucleus solely by something called the strong force, one of the four fundamental forces of nature. As its name implies, the force is indeed very strong, but only at very close range — it drops off so rapidly as to be negligible beyond 1/10,000 the size of an atom. But now, researchers at MIT have found that neutrons can actually be made to cling to particles called quantum dots, which are made up of tens of thousands of atomic nuclei, held there just by the strong force.

The new finding may lead to useful new tools for probing the basic properties of materials at the quantum level, including those arising from the strong force, as well as exploring new kinds of quantum information processing devices. The work is reported this week in the journal ACS Nano, in a paper by MIT graduate students Hao Tang and Guoqing Wang and MIT professors Ju Li and Paola Cappellaro of the Department of Nuclear Science and Engineering.

Neutrons are widely used to probe material properties using a method called neutron scattering, in which a beam of neutrons is focused on a sample, and the neutrons that bounce off the material’s atoms can be detected to reveal the material’s internal structure and dynamics.

But until this new work, nobody thought that these neutrons might actually stick to the materials they were probing. “The fact that [the neutrons] can be trapped by the materials, nobody seems to know about that,” says Li, who is also a professor of materials science and engineering. “We were surprised that this exists, and that nobody had talked about it before, among the experts we had checked with,” he says.

The reason this new finding is so surprising, Li explains, is because neutrons don’t interact with electromagnetic forces. Of the four fundamental forces, gravity and the weak force “are generally not important for materials,” he says. “Pretty much everything is electromagnetic interaction, but in this case, since the neutron doesn’t have a charge, the interaction here is through the strong interaction, and we know that is very short-range. It is effective at a range of 10 to the minus 15 power,” or one quadrillionth, of a meter.

“It’s very small, but it’s very intense,” he says of this force that holds the nuclei of atoms together. “But what’s interesting is we’ve got these many thousands of nuclei in this neutronic quantum dot, and that’s able to stabilize these bound states, which have much more diffuse wavefunctions at tens of nanometers [billionths of a meter].  These neutronic bound states in a quantum dot are actually quite akin to Thomson’s plum pudding model of an atom, after his discovery of the electron.”

It was so unexpected, Li calls it “a pretty crazy solution to a quantum mechanical problem.” The team calls the newly discovered state an artificial “neutronic molecule.”

These neutronic molecules are made from quantum dots, which are tiny crystalline particles, collections of atoms so small that their properties are governed more by the exact size and shape of the particles than by their composition. The discovery and controlled production of quantum dots were the subject of the 2023 Nobel Prize in Chemistry, awarded to MIT Professor Moungi Bawendi and two others.

“In conventional quantum dots, an electron is trapped by the electromagnetic potential created by a macroscopic number of atoms, thus its wavefunction extends to about 10 nanometers, much larger than a typical atomic radius,” says Cappellaro. “Similarly, in these nucleonic quantum dots, a single neutron can be trapped by a nanocrystal, with a size well beyond the range of the nuclear force, and display similar quantized energies.” While these energy jumps give quantum dots their colors, the neutronic quantum dots could be used for storing quantum information.

This work is based on theoretical calculations and computational simulations. “We did it analytically in two different ways, and eventually also verified it numerically,” Li says. Although the effect had never been described before, he says, in principle there’s no reason it couldn’t have been found much sooner: “Conceptually, people should have already thought about it,” he says, but as far as the team has been able to determine, nobody did.

Part of the difficulty in doing the computations is the very different scales involved: The binding energy of a neutron to the quantum dots they were attaching to is about one-trillionth that of previously known conditions where the neutron is bound to a small group of nucleons. For this work, the team used an analytical tool called Green’s function to demonstrate that the strong force was sufficient to capture neutrons with a quantum dot with a minimum radius of 13 nanometers.

Then, the researchers did detailed simulations of specific cases, such as the use of a lithium hydride nanocrystal, a material being studied as a possible storage medium for hydrogen. They showed that the binding energy of the neutrons to the nanocrystal is dependent on the exact dimensions and shape of the crystal, as well as the nuclear spin polarizations of the nuclei compared to that of the neutron. They also calculated similar effects for thin films and wires of the material as opposed to particles.

But Li says that actually creating such neutronic molecules in the lab, which among other things requires specialized equipment to maintain temperatures in the range of a few thousandths of a Kelvin above absolute zero, is something that other researchers with the appropriate expertise will have to undertake.

Li notes that “artificial atoms” made up of assemblages of atoms that share properties and can behave in many ways like a single atom have been used to probe many properties of real atoms. Similarly, he says, these artificial molecules provide “an interesting model system” that might be used to study “interesting quantum mechanical problems that one can think about,” such as whether these neutronic molecules will have a shell structure that mimics the electron shell structure of atoms.

“One possible application,” he says, “is maybe we can precisely control the neutron state. By changing the way the quantum dot oscillates, maybe we can shoot the neutron off in a particular direction.” Neutrons are powerful tools for such things as triggering both fission and fusion reactions, but so far it has been difficult to control individual neutrons. These new bound states could provide much greater degrees of control over individual neutrons, which could play a role in the development of new quantum information systems, he says.

“One idea is to use it to manipulate the neutron, and then the neutron will be able to affect other nuclear spins,” Li says. In that sense, he says, the neutronic molecule could serve as a mediator between the nuclear spins of separate nuclei — and this nuclear spin is a property that is already being used as a basic storage unit, or qubit, in developing quantum computer systems.

“The nuclear spin is like a stationary qubit, and the neutron is like a flying qubit,” he says. “That’s one potential application.” He adds that this is “quite different from electromagnetics-based quantum information processing, which is so far the dominant paradigm. So, regardless of whether it’s superconducting qubits or it’s trapped ions or nitrogen vacancy centers, most of these are based on electromagnetic interactions.” In this new system, instead, “we have neutrons and nuclear spin. We’re just starting to explore what we can do with it now.”

Another possible application, he says, is for a kind of imaging, using neutral activation analysis. “Neutron imaging complements X-ray imaging because neutrons are much more strongly interacting with light elements,” Li says. It can also be used for materials analysis, which can provide information not only about elemental composition but even about the different isotopes of those elements. “A lot of the chemical imaging and spectroscopy doesn’t tell us about the isotopes,” whereas the neutron-based method could do so, he says.

The research was supported by the U.S. Office of Naval Research.

A new set of advanced nanofabrication equipment will make MIT.nano one of the world’s most advanced research facilities in microelectronics and related technologies, unlocking new opportunities for experimentation and widening the path for promising inventions to become impactful new products.

The equipment, provided by Applied Materials, will significantly expand MIT.nano’s nanofabrication capabilities, making them compatible with wafers — thin, round slices of semiconductor material — up to 200 millimeters, or 8 inches, in diameter, a size widely used in industry. The new tools will allow researchers to prototype a vast array of new microelectronic devices using state-of-the-art materials and fabrication processes. At the same time, the 200-millimeter compatibility will support close collaboration with industry and enable innovations to be rapidly adopted by companies and mass produced.

MIT.nano’s leaders say the equipment, which will also be available to scientists outside of MIT, will dramatically enhance their facility’s capabilities, allowing experts in the region to more efficiently explore new approaches in “tough tech” sectors, including advanced electronics, next-generation batteries, renewable energies, optical computing, biological sensing, and a host of other areas — many likely yet to be imagined.

“The toolsets will provide an accelerative boost to our ability to launch new technologies that can then be given to the world at scale,” says MIT.nano Director Vladimir Bulović, who is also the Fariborz Maseeh Professor of Emerging Technology. “MIT.nano is committed to its expansive mission — to build a better world. We provide toolsets and capabilities that, in the hands of brilliant researchers, can effectively move the world forward.”

The announcement comes as part of an agreement between MIT and Applied Materials, Inc. that, together with a grant to MIT from the Northeast Microelectronics Coalition (NEMC) Hub, commits more than $40 million of estimated private and public investment to add advanced nano-fabrication equipment and capabilities at MIT.nano.

“We don’t believe there is another space in the United States that will offer the same kind of versatility, capability, and accessibility, with 8-inch toolsets integrated right next to more fundamental toolsets for research discoveries,” Bulović says. “It will create a seamless path to accelerate the pace of innovation.”

Pushing the boundaries of innovation

Applied Materials is the world’s largest supplier of equipment for manufacturing semiconductors, displays, and other advanced electronics. The company will provide at MIT.nano several state-of-the-art process tools capable of supporting 150- and 200-millimeter wafers and will enhance and upgrade an existing tool owned by MIT. In addition to assisting MIT.nano in the day-to-day operation and maintenance of the equipment, Applied Materials engineers will develop new process capabilities to benefit researchers and students from MIT and beyond.

“This investment will significantly accelerate the pace of innovation and discovery in microelectronics and microsystems,” says Tomás Palacios, director of MIT’s Microsystems Technology Laboratories and the Clarence J. Lebel Professor in Electrical Engineering. “It’s wonderful news for our community, wonderful news for the state, and, in my view, a tremendous step forward toward implementing the national vision for the future of innovation in microelectronics.”

Nanoscale research at universities is traditionally conducted on machines that are less compatible with industry, which makes academic innovations more difficult to turn into impactful, mass-produced products. Jorg Scholvin, associate director for MIT.nano’s shared fabrication facility, says the new machines, when combined with MIT.nano’s existing equipment, represent a step-change improvement in that area: Researchers will be able to take an industry-standard wafer and build their technology on top of it to prove to companies it works on existing devices, or to co-fabricate new ideas in close collaboration with industry partners.

“In the journey from an idea to a fully working device, the ability to begin on a small scale, figure out what you want to do, rapidly debug your designs, and then scale it up to an industry-scale wafer is critical,” Scholvin says. “It means a student can test out their idea on wafer-scale quickly and directly incorporate insights into their project so that their processes are scalable. Providing such proof-of-principle early on will accelerate the idea out of the academic environment, potentially reducing years of added effort. Other tools at MIT.nano can supplement work on the 200-millimeter wafer scale, but the higher throughput and higher precision of the Applied equipment will provide researchers with repeatability and accuracy that is unprecedented for academic research environments. Essentially what you have is a sharper, faster, more precise tool to do your work.”

Scholvin predicts the equipment will lead to exponential growth in research opportunities.

“I think a key benefit of these tools is they allow us to push the boundary of research in a variety of different ways that we can predict today,” Scholvin says. “But then there are also unpredictable benefits, which are hiding in the shadows waiting to be discovered by the creativity of the researchers at MIT. With each new application, more ideas and paths usually come to mind — so that over time, more and more opportunities are discovered.”

Because the equipment is available for use by people outside of the MIT community, including regional researchers, industry partners, nonprofit organizations, and local startups, they will also enable new collaborations.

“The tools themselves will be an incredible meeting place — a place that can, I think, transpose the best of our ideas in a much more effective way than before,” Bulović says. “I’m extremely excited about that.”

Palacios notes that while microelectronics is best known for work making transistors smaller to fit on microprocessors, it’s a vast field that enables virtually all the technology around us, from wireless communications and high-speed internet to energy management, personalized health care, and more.

He says he’s personally excited to use the new machines to do research around power electronics and semiconductors, including exploring promising new materials like gallium nitride, which could dramatically improve the efficiency of electronic devices.

Fulfilling a mission

MIT.nano’s leaders say a key driver of commercialization will be startups, both from MIT and beyond.

“This is not only going to help the MIT research community innovate faster, it’s also going to enable a new wave of entrepreneurship,” Palacios says. “We’re reducing the barriers for students, faculty, and other entrepreneurs to be able to take innovation and get it to market. That fits nicely with MIT’s mission of making the world a better place through technology. I cannot wait to see the amazing new inventions that our colleagues and students will come out with.”

Bulović says the announcement aligns with the mission laid out by MIT’s leaders at MIT.nano’s inception.

"We have the space in MIT.nano to accommodate these tools, we have the capabilities inside MIT.nano to manage their operation, and as a shared and open facility, we have methodologies by which we can welcome anyone from the region to use the tools,” Bulović says. “That is the vision MIT laid out as we were designing MIT.nano, and this announcement helps to fulfill that vision.”

Metaphysics is the branch of philosophy that deals in the deep scaffolding of the world: the nature of space, time, causation and existence, the foundations of reality itself. It’s generally considered untestable, since metaphysical assumptions underlie all our efforts to conduct tests and interpret results. Those assumptions usually go unspoken. Most of the time, that’s fine.

Source

I create a modelinstance in Libgdx that I call yellowInstance. The modelinstance is defined as follows: I need it to fall down under the force of gravity, But it just stays in the air!

 ModelBuilder yellowBuilder = new ModelBuilder();
            yellowBuilder.begin();
            Node nod = yellowBuilder.node();
            nod.id = "yellowboxy";
            Material yellowMat = new Material();
            yellowMat.set(PBRColorAttribute.createBaseColorFactor(Color.YELLOW));
            MeshPartBuilder yellowPartBuilder = yellowBuilder.part("yellowboxy", GL20.GL_TRIANGLES, VertexAttributes.Usage.Position | VertexAttributes.Usage.Normal, yellowMat);
            BoxShapeBuilder.build(yellowPartBuilder, 10f, 20f, 10f, 2f, 2f, 2f);
            yellowInstance = new ModelInstance(yellowBuilder.end());

I create the physics for it using Bullet Physics library as such:

btCollisionShape btBox = new btBoxShape(new Vector3(1,1,1)); //notice we take halves!
    Vector3 localInertia = new Vector3();
    btBox.calculateLocalInertia(5f,localInertia);

    //MotionStateForPhys msphys = new MotionStateForPhys(yellowInstance.transform);

    btRigidBody.btRigidBodyConstructionInfo info = new btRigidBody.btRigidBodyConstructionInfo(5f,null,btBox,localInertia);
    btRigidBody btYellowBody = new btRigidBody(info);

    /*btYellowBody.setMotionState(msphys);*/

    btYellowBody.setWorldTransform(yellowInstance.transform);

    dynamicsWorld.addRigidBody(btYellowBody);

    btYellowBody.activate(true);

here are the definitions for the important physics variables needed by the library

private btCollisionConfiguration collisionConfiguration;
private com.badlogic.gdx.physics.bullet.collision.btDispatcher btDispatcher;
private btDiscreteDynamicsWorld dynamicsWorld;
private btSequentialImpulseConstraintSolver solver;

collisionConfiguration = new btDefaultCollisionConfiguration();
    btDispatcher = new btCollisionDispatcher(collisionConfiguration);
    btInterface = new btDbvtBroadphase();
    solver = new btSequentialImpulseConstraintSolver();
    dynamicsWorld = new 
btDiscreteDynamicsWorld(btDispatcher,btInterface,solver,collisionConfiguration);
    dynamicsWorld.setGravity(new Vector3(0,-10f,0));

Here is how I update the timeStep for the Physics library:

private void update(float deltatime){
btYellowBody.activate(true);
    dynamicsWorld.stepSimulation(deltatime , 5 , 1/60f);

} 

Here is my render method that calls the update method where my Physics variables are:

inputHandler.UpdateAfterKeyPress(Gdx.graphics.getDeltaTime(),"levelone");
    
    worldBuilder.update(delta); //will update the physics in levelone!

    Gdx.gl.glClearColor(0, .25f, 0, 1);
    Gdx.gl.glClear(GL20.GL_COLOR_BUFFER_BIT);

    ScreenUtils.clear(BACKGROUND_COLOUR, true);

managerScenes.update(Gdx.graphics.getDeltaTime());
    managerScenes.render();

if (Gdx.input.isKeyJustPressed(Input.Keys.ESCAPE))
        Gdx.app.exit();

EDIT: IF I REMOVE THE FLOOR FROM THE PHYSICS SIMULATION, THE YELLOW BOX FALLS UNDER THE FORCE OF GRAVITY! WHY REMOVING THE FLOOR WILL MAKE THE BOX FALL DOWN!

this is how the floor is added: THERE IS SOMETHING I'M MISSING HERE!!

ModelBuilder mBuilder = new ModelBuilder();
    mBuilder.begin();

    // Start a new node with a specific name
    Node node = mBuilder.node();
    node.id = "floory"; // Set the node's id

    Material mat = new Material();
    mat.set(PBRColorAttribute.createBaseColorFactor(Color.BLACK));
    MeshPartBuilder mpartbuilder = mBuilder.part("floory", GL20.GL_TRIANGLES, VertexAttributes.Usage.Position|VertexAttributes.Usage.Normal,mat);
    BoxShapeBuilder.build(mpartbuilder,0,-0.5f,0,300f,1f,400f);
    ModelInstance mInstance = new ModelInstance(mBuilder.end());

    sManager.addScene(new Scene(mInstance));

    //create the physics id and body/shape properties
   

    btCollisionShape shape = Bullet.obtainStaticNodeShape(mInstance.nodes);


    btBoxShape/*btCollisionShape*/ btBox = new btBoxShape(new Vector3(150,0.5f,200)); //notice we take halves!
    btRigidBody.btRigidBodyConstructionInfo info = new btRigidBody.btRigidBodyConstructionInfo(0,null,btBox,Vector3.Zero);
    btRigidBody btBody = new btRigidBody(info);
    btBody.setWorldTransform(mInstance.transform);
  

    dynamicsWorld.addCollisionObject(btBody);

Metaphysics is the branch of philosophy that deals in the deep scaffolding of the world: the nature of space, time, causation and existence, the foundations of reality itself. It’s generally considered untestable, since metaphysical assumptions underlie all our efforts to conduct tests and interpret results. Those assumptions usually go unspoken. Most of the time, that’s fine.

Source

A material with a high electron mobility is like a highway without traffic. Any electrons that flow into the material experience a commuter’s dream, breezing through without any obstacles or congestion to slow or scatter them off their path.

The higher a material’s electron mobility, the more efficient its electrical conductivity, and the less energy is lost or wasted as electrons zip through. Advanced materials that exhibit high electron mobility will be essential for more efficient and sustainable electronic devices that can do more work with less power.

Now, physicists at MIT, the Army Research Lab, and elsewhere have achieved a record-setting level of electron mobility in a thin film of ternary tetradymite — a class of mineral that is naturally found in deep hydrothermal deposits of gold and quartz.

For this study, the scientists grew pure, ultrathin films of the material, in a way that minimized defects in its crystalline structure. They found that this nearly perfect film — much thinner than a human hair — exhibits the highest electron mobility in its class.

The team was able to estimate the material’s electron mobility by detecting quantum oscillations when electric current passes through. These oscillations are a signature of the quantum mechanical behavior of electrons in a material. The researchers detected a particular rhythm of oscillations that is characteristic of high electron mobility — higher than any ternary thin films of this class to date.

“Before, what people had achieved in terms of electron mobility in these systems was like traffic on a road under construction — you’re backed up, you can’t drive, it’s dusty, and it’s a mess,” says Jagadeesh Moodera, a senior research scientist in MIT’s Department of Physics. “In this newly optimized material, it’s like driving on the Mass Pike with no traffic.”

The team’s results, which appear today in the journal Materials Today Physics, point to ternary tetradymite thin films as a promising material for future electronics, such as wearable thermoelectric devices that efficiently convert waste heat into electricity. (Tetradymites are the active materials that cause the cooling effect in commercial thermoelectric coolers.) The material could also be the basis for spintronic devices, which process information using an electron’s spin, using far less power than conventional silicon-based devices.

The study also uses quantum oscillations as a highly effective tool for measuring a material’s electronic performance.

“We are using this oscillation as a rapid test kit,” says study author Hang Chi, a former research scientist at MIT who is now at the University of Ottawa. “By studying this delicate quantum dance of electrons, scientists can start to understand and identify new materials for the next generation of technologies that will power our world.”

Chi and Moodera’s co-authors include Patrick Taylor, formerly of MIT Lincoln Laboratory, along with Owen Vail and Harry Hier of the Army Research Lab, and Brandi Wooten and Joseph Heremans of Ohio State University.

Beam down

The name “tetradymite” derives from the Greek “tetra” for “four,” and “dymite,” meaning “twin.” Both terms describe the mineral’s crystal structure, which consists of rhombohedral crystals that are “twinned” in groups of four — i.e. they have identical crystal structures that share a side.

Tetradymites comprise combinations of bismuth, antimony tellurium, sulfur, and selenium. In the 1950s, scientists found that tetradymites exhibit semiconducting properties that could be ideal for thermoelectric applications: The mineral in its bulk crystal form was able to passively convert heat into electricity.

Then, in the 1990s, the late Institute Professor Mildred Dresselhaus proposed that the mineral’s thermoelectric properties might be significantly enhanced, not in its bulk form but within its microscopic, nanometer-scale surface, where the interactions of electrons is more pronounced. (Heremans happened to work in Dresselhaus’ group at the time.)

“It became clear that when you look at this material long enough and close enough, new things will happen,” Chi says. “This material was identified as a topological insulator, where scientists could see very interesting phenomena on their surface. But to keep uncovering new things, we have to master the material growth.”

To grow thin films of pure crystal, the researchers employed molecular beam epitaxy — a method by which a beam of molecules is fired at a substrate, typically in a vacuum, and with precisely controlled temperatures. When the molecules deposit on the substrate, they condense and build up slowly, one atomic layer at a time. By controlling the timing and type of molecules deposited, scientists can grow ultrathin crystal films in exact configurations, with few if any defects.

“Normally, bismuth and tellurium can interchange their position, which creates defects in the crystal,” co-author Taylor explains. “The system we used to grow these films came down with me from MIT Lincoln Laboratory, where we use high purity materials to minimize impurities to undetectable limits. It is the perfect tool to explore this research.”

Free flow

The team grew thin films of ternary tetradymite, each about 100 nanometers thin. They then tested the film’s electronic properties by looking for Shubnikov-de Haas quantum oscillations — a phenomenon that was discovered by physicists Lev Shubnikov and Wander de Haas, who found that a material’s electrical conductivity can oscillate when exposed to a strong magnetic field at low temperatures. This effect occurs because the material’s electrons fill up specific energy levels that shift as the magnetic field changes.

Such quantum oscillations could serve as a signature of a material’s electronic structure, and the ways in which electrons behave and interact. Most notably for the MIT team, the oscillations could determine a material’s electron mobility: If oscillations exist, it must mean that the material’s electrical resistance is able to change, and by inference, electrons can be mobile, and made to easily flow.

The team looked for signs of quantum oscillations in their new films, by first exposing them to ultracold temperatures and a strong magnetic field, then running an electric current through the film and measuring the voltage along its path, as they tuned the magnetic field up and down.

“It turns out, to our great joy and excitement, that the material’s electrical resistance oscillates,” Chi says. “Immediately, that tells you that this has very high electron mobility.”

Specifically, the team estimates that the ternary tetradymite thin film exhibits an electron mobility of 10,000 cm²/V-s — the highest mobility of any ternary tetradymite film yet measured. The team suspects that the film’s record mobility has something to do with its low defects and impurities, which they were able to minimize with their precise growth strategies. The fewer a material’s defects, the fewer obstacles an electron encounters, and the more freely it can flow.

“This is showing it’s possible to go a giant step further, when properly controlling these complex systems,” Moodera says. “This tells us we’re in the right direction, and we have the right system to proceed further, to keep perfecting this material down to even much thinner films and proximity coupling for use in future spintronics and wearable thermoelectric devices.”

This research was supported in part by the Army Research Office, National Science Foundation, Office of Naval Research, Canada Research Chairs Program and Natural Sciences and Engineering Research Council of Canada.

MIT faculty members Nancy Kanwisher, Robert Langer, and Sara Seager are among eight researchers worldwide to receive this year’s Kavli Prizes.

A partnership among the Norwegian Academy of Science and Letters, the Norwegian Ministry of Education and Research, and the Kavli Foundation, the Kavli Prizes are awarded every two years to “honor scientists for breakthroughs in astrophysics, nanoscience and neuroscience that transform our understanding of the big, the small and the complex.” The laureates in each field will share $1 million.

Understanding recognition of faces

Nancy Kanwisher, the Walter A Rosenblith Professor of Brain and Cognitive Sciences and McGovern Institute for Brain Research investigator, has been awarded the 2024 Kavli Prize in Neuroscience with Doris Tsao, professor in the Department of Molecular and Cell Biology at the University of California at Berkeley, and Winrich Freiwald, the Denise A. and Eugene W. Chinery Professor at the Rockefeller University.

Kanwisher, Tsao, and Freiwald discovered a specialized system within the brain to recognize faces. Their discoveries have provided basic principles of neural organization and made the starting point for further research on how the processing of visual information is integrated with other cognitive functions.

Kanwisher was the first to prove that a specific area in the human neocortex is dedicated to recognizing faces, now called the fusiform face area. Using functional magnetic resonance imaging, she found individual differences in the location of this area and devised an analysis technique to effectively localize specialized functional regions in the brain. This technique is now widely used and applied to domains beyond the face recognition system. 

Integrating nanomaterials for biomedical advances

Robert Langer, the David H. Koch Institute Professor, has been awarded the 2024 Kavli Prize in Nanoscience with Paul Alivisatos, president of the University of Chicago and John D. MacArthur Distinguished Service Professor in the Department of Chemistry, and Chad Mirkin, professor of chemistry at Northwestern University.

Langer, Alivisatos, and Mirkin each revolutionized the field of nanomedicine by demonstrating how engineering at the nano scale can advance biomedical research and application. Their discoveries contributed foundationally to the development of therapeutics, vaccines, bioimaging, and diagnostics.

Langer was the first to develop nanoengineered materials that enabled the controlled release, or regular flow, of drug molecules. This capability has had an immense impact for the treatment of a range of diseases, such as aggressive brain cancer, prostate cancer, and schizophrenia. His work also showed that tiny particles, containing protein antigens, can be used in vaccination, and was instrumental in the development of the delivery of messenger RNA vaccines. 

Searching for life beyond Earth

Sara Seager, the Class of 1941 Professor of Planetary Sciences in the Department of Earth, Atmospheric and Planetary Sciences and a professor in the departments of Physics and of Aeronautics and Astronautics, has been awarded the 2024 Kavli Prize in Astrophysics along with David Charbonneau, the Fred Kavli Professor of Astrophysics at Harvard University.

Seager and Charbonneau are recognized for discoveries of exoplanets and the characterization of their atmospheres. They pioneered methods for the detection of atomic species in planetary atmospheres and the measurement of their thermal infrared emission, setting the stage for finding the molecular fingerprints of atmospheres around both giant and rocky planets. Their contributions have been key to the enormous progress seen in the last 20 years in the exploration of myriad exoplanets. 

Kanwisher, Langer, and Seager bring the number of all-time MIT faculty recipients of the Kavli Prize to eight. Prior winners include Rainer Weiss in astrophysics (2016), Alan Guth in astrophysics (2014), Mildred Dresselhaus in nanoscience (2012), Ann Graybiel in neuroscience (2012), and Jane Luu in astrophysics (2012).

MIT physicists and colleagues have created a five-lane superhighway for electrons that could allow ultra-efficient electronics and more. 

The work, reported in the May 10 issue of Science, is one of several important discoveries by the same team over the past year involving a material that is a unique form of graphene.

“This discovery has direct implications for low-power electronic devices because no energy is lost during the propagation of electrons, which is not the case in regular materials where the electrons are scattered,” says Long Ju, an assistant professor in the Department of Physics and corresponding author of the Science paper.

The phenomenon is akin to cars traveling down an open turnpike as opposed to those moving through neighborhoods. The neighborhood cars can be stopped or slowed by other drivers making abrupt stops or U-turns that disrupt an otherwise smooth commute.

A new material

The material behind this work, known as rhombohedral pentalayer graphene, was discovered two years ago by physicists led by Ju. “We found a goldmine, and every scoop is revealing something new,” says Ju, who is also affiliated with MIT’s Materials Research Laboratory.

In a Nature Nanotechnology paper last October, Ju and colleagues reported the discovery of three important properties arising from rhombohedral graphene. For example, they showed that it could be topological, or allow the unimpeded movement of electrons around the edge of the material but not through the middle. That resulted in a superhighway, but required the application of a large magnetic field some tens of thousands times stronger than the Earth’s magnetic field.

In the current work, the team reports creating the superhighway without any magnetic field.

Tonghang Han, an MIT graduate student in physics, is a co-first author of the paper. “We are not the first to discover this general phenomenon, but we did so in a very different system. And compared to previous systems, ours is simpler and also supports more electron channels.” Explains Ju, “other materials can only support one lane of traffic on the edge of the material. We suddenly bumped it up to five.”

Additional co-first authors of the paper who contributed equally to the work are Zhengguang Lu and Yuxuan Yao. Lu is a postdoc in the Materials Research Laboratory. Yao conducted the work as a visiting undergraduate student from Tsinghua University. Other authors are MIT professor of physics Liang Fu; Jixiang Yang and Junseok Seo, both MIT graduate students in physics; Chiho Yoon and Fan Zhang of the University of Texas at Dallas; and Kenji Watanabe and Takashi Taniguchi of the National Institute for Materials Science in Japan.

How it works

Graphite, the primary component of pencil lead, is composed of many layers of graphene, a single layer of carbon atoms arranged in hexagons resembling a honeycomb structure. Rhombohedral graphene is composed of five layers of graphene stacked in a specific overlapping order.

Ju and colleagues isolated rhombohedral graphene thanks to a novel microscope Ju built at MIT in 2021 that can quickly and relatively inexpensively determine a variety of important characteristics of a material at the nanoscale. Pentalayer rhombohedral stacked graphene is only a few billionths of a meter thick.

In the current work, the team tinkered with the original system, adding a layer of tungsten disulfide (WS₂). “The interaction between the WS₂ and the pentalayer rhombohedral graphene resulted in this five-lane superhighway that operates at zero magnetic field,” says Ju.

Comparison to superconductivity

The phenomenon that the Ju group discovered in rhombohedral graphene that allows electrons to travel with no resistance at zero magnetic field is known as the quantum anomalous Hall effect. Most people are more familiar with superconductivity, a completely different phenomenon that does the same thing but happens in very different materials.

Ju notes that although superconductors were discovered in the 1910s, it took some 100 years of research to coax the system to work at the higher temperatures necessary for applications. “And the world record is still well below room temperature,” he notes.

Similarly, the rhombohedral graphene superhighway currently operates at about 2 kelvins, or -456 degrees Fahrenheit. “It will take a lot of effort to elevate the temperature, but as physicists, our job is to provide the insight; a different way for realizing this [phenomenon],” Ju says.

Very exciting

The discoveries involving rhombohedral graphene came as a result of painstaking research that wasn’t guaranteed to work. “We tried many recipes over many months,” says Han, “so it was very exciting when we cooled the system to a very low temperature and [a five-lane superhighway operating at zero magnetic field] just popped out.”

Says Ju, “it’s very exciting to be the first to discover a phenomenon in a new system, especially in a material that we uncovered.”

This work was supported by a Sloan Fellowship; the U.S. National Science Foundation; the U.S. Office of the Under Secretary of Defense for Research and Engineering; the Japan Society for the Promotion of Science KAKENHI; and the World Premier International Research Initiative of Japan.

Physics graduate student Jeong Min (Jane) Park is among the 32 exceptional early-career scientists worldwide chosen to receive the prestigious 2024 Schmidt Science Fellows award.  

As a 2024 Schmidt Science Fellow, Park’s postdoctoral work will seek to directly detect phases that could host new particles by employing an instrument that can visualize subatomic-scale phenomena.  

With her advisor, Pablo Jarillo-Herrero, the Cecil and Ida Green Professor of Physics, Park’s research at MIT focuses on discovering novel quantum phases of matter.

“When there are many electrons in a material, their interactions can lead to collective behaviors that are not expected from individual particles, known as emergent phenomena,” explains Park. “One example is superconductivity, where interacting electrons combine together as a pair at low temperatures to conduct electricity without energy loss.”

During her PhD studies, she has investigated novel types of superconductivity by designing new materials with targeted interactions and topology. In particular, she used graphene, atomically thin two-dimensional layers of graphite, the same material as pencil lead, and turned it into a “magic” material. This so-called magic-angle twisted trilayer graphene provided an extraordinarily strong form of superconductivity that is robust under high magnetic fields. Later, she found a whole “magic family” of these materials, elucidating the key mechanisms behind superconductivity and interaction-driven phenomena. These results have provided a new platform to study emergent phenomena in two dimensions, which can lead to innovations in electronics and quantum technology.

Park says she is looking forward to her postdoctoral studies with Princeton University physics professor Ali Yazdani's lab.

“I’m excited about the idea of discovering and studying new quantum phenomena that could further the understanding of fundamental physics,” says Park. “Having explored interaction-driven phenomena through the design of new materials, I’m now aiming to broaden my perspective and expertise to address a different kind of question, by combining my background in material design with the sophisticated local-scale measurements that I will adopt during my postdoc.”

She explains that elementary particles are classified as either bosons or fermions, with contrasting behaviors upon interchanging two identical particles, referred to as exchange statistics; bosons remain unchanged, while fermions acquire a minus sign in their quantum wavefunction.

Theories predict the existence of fundamentally different particles known as non-abelian anyons, whose wavefunctions braid upon particle exchange. Such a braiding process can be used to encode and store information, potentially opening the door to fault-tolerant quantum computing in the future.

Since 2018, this prestigious postdoctoral program has sought to break down silos among scientific fields to solve the world’s biggest challenges and support future leaders in STEM.

Schmidt Science Fellows, an initiative of Schmidt Sciences, delivered in partnership with the Rhodes Trust, identifies, develops, and amplifies the next generation of science leaders, by building a community of scientists and supporters of interdisciplinary science and leveraging this network to drive sector-wide change. The 2024 fellows consist of 17 nationalities across North America, Europe, and Asia.   

Nominated candidates undergo a rigorous selection process that includes a paper-based academic review with panels of experts in their home disciplines and final interviews with panels, including senior representatives from across many scientific disciplines and different business sectors.  

John Joannopoulos, an innovator and mentor in the fields of theoretical condensed matter physics and nanophotonics, has been named the recipient of the 2024-2025 James R. Killian Jr. Faculty Achievement Award.

Joannopoulos is the Francis Wright Davis Professor of Physics and director of MIT’s Institute for Soldier Nanotechnologies. He has been a member of the MIT faculty for 50 years.

“Professor Joannopoulos’s profound and lasting impact on the field of theoretical condensed matter physics finds its roots in his pioneering work in harnessing ab initio physics to elucidate the behavior of materials at the atomic level,” states the award citation, which was announced at today’s faculty meeting by Roger White, chair of the Killian Award Selection Committee and professor of philosophy at MIT. “His seminal research in the development of photonic crystals has revolutionized understanding of light-matter interactions, laying the groundwork for transformative advancements in diverse fields ranging from telecommunications to biomedical engineering.”

The award also honors Joannopoulos’ service as a “legendary mentor to generations of students, inspiring them to achieve excellence in science while at the same time facilitating the practical benefit to society through entrepreneurship.”

The Killian Award was established in 1971 to recognize outstanding professional contributions by MIT faculty members. It is the highest honor that the faculty can give to one of its members.

“I have to tell you, it was a complete and utter surprise,” Joannopoulos told MIT News shortly after he received word of the award. “I didn’t expect it at all, and was extremely flattered, honored, and moved by it, frankly.”

Joannopoulous has spent his entire professional career at MIT. He came to the Institute in 1974, directly after receiving his PhD in physics at the University of California at Berkeley, where he also earned his bachelor’s degree. Starting out as an assistant professor in MIT’s Department of Physics, he quickly set up a research program focused on theoretical condensed matter physics.

Over the first half of his MIT career, Joannopoulos worked to elucidate the fundamental nature of the electronic, vibrational, and optical structure of crystalline and amorphous bulk solids, their surfaces, interfaces, and defects. He and his students developed numerous theoretical methods to enable tractable and accurate calculations of these complex systems.

In the 1990s, his work with microscopic material systems expanded to a new class of materials, called photonic crystals — materials that could be engineered at the micro- and nanoscale to manipulate light in ways that impart surprising and exotic optical qualities to the material as a whole.

“I saw that you could create photonic crystals with defects that can affect the properties of photons, in much the same way that defects in a semiconductor affect the properties of electrons,” Joannopoulos says. “So I started working in this area to try and explore what anomalous light phenomena can we discover using this approach?”

Among his various breakthroughs in the field was the realization of a “perfect dielectric mirror” — a multilayered optical device that reflects light from all angles as normal metallic mirrors do, and that can also be tuned to reflect and trap light at specific frequencies. He and his colleagues saw potential for the mirror to be made into a hollow fiber that could serve as a highly effective optical conduit, for use in a wide range of applications. To further advance the technology, he and his colleagues launched a startup, which has since developed the technology into a flexible, fiber-optic “surgical scalpel.”

Throughout his career, Joannopoulos has helped to launch numerous startups and photonics-based technologies.

“His ability to bridge the gap between academia and industry has not only advanced scientific knowledge but also led to the creation of dozens of new companies, thousands of jobs, and groundbreaking products that continue to benefit society to this day,” the award citation states.

In 2006, Joannopoulos accepted the position as director of MIT’s Institute for Soldier Nanotechnologies (ISN), a collaboration between MIT researchers, industry partners, and military defense experts, who seek innovations to protect and enhance soldiers’ survivability in the field. In his role as ISN head, Joannopoulos has worked across MIT, making connections and supporting new projects with researchers specializing in fields far from his own.

“I get a chance to explore and learn fascinating new things,” says Joannopoulos, who is currently overseeing projects related to hyperspectral imaging, smart and responsive fabrics, and nanodrug delivery. “I love that aspect of really getting to understand what people in other fields are doing. And they’re doing great work across many, many different fields.”

Throughout his career at MIT, Joannopoulos has been especially inspired and motivated by his students, many of whom have gone on to found companies, lead top academic and research institutions, and make significant contributions to their respective fields, including one student who was awarded the Nobel Prize in Physics in 1998.

“One’s proudest moments are the successes of one’s students, and in that regard, I’ve been extremely lucky to have had truly exceptional students over the years,” Joannopolous says.

His many contributions to academia and industry have earned Joannopoulos numerous honors and awards, including his election to both the National Academy of Sciences and the American Academy of Arts and Sciences. He is also a fellow of both the American Physical Society and the American Association for the Advancement of Science.

“The Selection Committee is delighted to have this opportunity to honor Professor John Joannopoulos: a visionary scientist, a beloved mentor, a great believer in the goodness of people, and a leader whose contributions to MIT and the broader scientific community are immeasurable,” the award citation concludes.

Proximity is key for many quantum phenomena, as interactions between atoms are stronger when the particles are close. In many quantum simulators, scientists arrange atoms as close together as possible to explore exotic states of matter and build new quantum materials.

They typically do this by cooling the atoms to a stand-still, then using laser light to position the particles as close as 500 nanometers apart — a limit that is set by the wavelength of light. Now, MIT physicists have developed a technique that allows them to arrange atoms in much closer proximity, down to a mere 50 nanometers. For context, a red blood cell is about 1,000 nanometers wide.

The physicists demonstrated the new approach in experiments with dysprosium, which is the most magnetic atom in nature. They used the new approach to manipulate two layers of dysprosium atoms, and positioned the layers precisely 50 nanometers apart. At this extreme proximity, the magnetic interactions were 1,000 times stronger than if the layers were separated by 500 nanometers.

What’s more, the scientists were able to measure two new effects caused by the atoms’ proximity. Their enhanced magnetic forces caused “thermalization,” or the transfer of heat from one layer to another, as well as synchronized oscillations between layers. These effects petered out as the layers were spaced farther apart.

“We have gone from positioning atoms from 500 nanometers to 50 nanometers apart, and there is a lot you can do with this,” says Wolfgang Ketterle, the John D. MacArthur Professor of Physics at MIT. “At 50 nanometers, the behavior of atoms is so much different that we’re really entering a new regime here.”

Ketterle and his colleagues say the new approach can be applied to many other atoms to study quantum phenomena. For their part, the group plans to use the technique to manipulate atoms into configurations that could generate the first purely magnetic quantum gate — a key building block for a new type of quantum computer.

The team has published their results today in the journal Science. The study’s co-authors include lead author and physics graduate student Li Du, along with Pierre Barral, Michael Cantara, Julius de Hond, and Yu-Kun Lu — all members of the MIT-Harvard Center for Ultracold Atoms, the Department of Physics, and the Research Laboratory of Electronics at MIT.

Peaks and valleys

To manipulate and arrange atoms, physicists typically first cool a cloud of atoms to temperatures approaching absolute zero, then use a system of laser beams to corral the atoms into an optical trap.

Laser light is an electromagnetic wave with a specific wavelength (the distance between maxima of the electric field) and frequency. The wavelength limits the smallest pattern into which light can be shaped to typically 500 nanometers, the so-called optical resolution limit. Since atoms are attracted by laser light of certain frequencies, atoms will be positioned at the points of peak laser intensity. For this reason, existing techniques have been limited in how close they can position atomic particles, and could not be used to explore phenomena that happen at much shorter distances.

“Conventional techniques stop at 500 nanometers, limited not by the atoms but by the wavelength of light,” Ketterle explains. “We have found now a new trick with light where we can break through that limit.”

The team’s new approach, like current techniques, starts by cooling a cloud of atoms — in this case, to about 1 microkelvin, just a hair above absolute zero — at which point, the atoms come to a near-standstill. Physicists can then use lasers to move the frozen particles into desired configurations.

Then, Du and his collaborators worked with two laser beams, each with a different frequency, or color, and circular polarization, or direction of the laser’s electric field. When the two beams travel through a super-cooled cloud of atoms, the atoms can orient their spin in opposite directions, following either of the two lasers’ polarization. The result is that the beams produce two groups of the same atoms, only with opposite spins.

Each laser beam formed a standing wave, a periodic pattern of electric field intensity with a spatial period of 500 nanometers. Due to their different polarizations, each standing wave attracted and corralled one of two groups of atoms, depending on their spin. The lasers could be overlaid and tuned such that the distance between their respective peaks is as small as 50 nanometers, meaning that the atoms gravitating to each respective laser’s peaks would be separated by the same 50 nanometers.

But in order for this to happen, the lasers would have to be extremely stable and immune to all external noise, such as from shaking or even breathing on the experiment. The team realized they could stabilize both lasers by directing them through an optical fiber, which served to lock the light beams in place in relation to each other.

“The idea of sending both beams through the optical fiber meant the whole machine could shake violently, but the two laser beams stayed absolutely stable with respect to each others,” Du says.

Magnetic forces at close range

As a first test of their new technique, the team used atoms of dysprosium — a rare-earth metal that is one of the strongest magnetic elements in the periodic table, particularly at ultracold temperatures. However, at the scale of atoms, the element’s magnetic interactions are relatively weak at distances of even 500 nanometers. As with common refrigerator magnets, the magnetic attraction between atoms increases with proximity, and the scientists suspected that if their new technique could space dysprosium atoms as close as 50 nanometers apart, they might observe the emergence of otherwise weak interactions between the magnetic atoms.

“We could suddenly have magnetic interactions, which used to be almost neglible but now are really strong,” Ketterle says.

The team applied their technique to dysprosium, first super-cooling the atoms, then passing two lasers through to split the atoms into two spin groups, or layers. They then directed the lasers through an optical fiber to stabilize them, and found that indeed, the two layers of dysprosium atoms gravitated to their respective laser peaks, which in effect separated the layers of atoms by 50 nanometers — the closest distance that any ultracold atom experiment has been able to achieve.

At this extremely close proximity, the atoms’ natural magnetic interactions were significantly enhanced, and were 1,000 times stronger than if they were positioned 500 nanometers apart. The team observed that these interactions resulted in two novel quantum phenomena: collective oscillation, in which one layer’s vibrations caused the other layer to vibrate in sync; and thermalization, in which one layer transferred heat to the other, purely through magnetic fluctuations in the atoms.

“Until now, heat between atoms could only by exchanged when they were in the same physical space and could collide,” Du notes. “Now we have seen atomic layers, separated by vacuum, and they exchange heat via fluctuating magnetic fields.”

The team’s results introduce a new technique that can be used to position many types of atom in close proximity. They also show that atoms, placed close enough together, can exhibit interesting quantum phenomena, that could be harnessed to build new quantum materials, and potentially, magnetically-driven atomic systems for quantum computers.

“We are really bringing super-resolution methods to the field, and it will become a general tool for doing quantum simulations,” Ketterle says. “There are many variants possible, which we are working on.”

This research was funded, in part, by the National Science Foundation and the Department of Defense.

Neutrons are subatomic particles that have no electric charge, unlike protons and electrons. That means that while the electromagnetic force is responsible for most of the interactions between radiation and materials, neutrons are essentially immune to that force.

Instead, neutrons are held together inside an atom’s nucleus solely by something called the strong force, one of the four fundamental forces of nature. As its name implies, the force is indeed very strong, but only at very close range — it drops off so rapidly as to be negligible beyond 1/10,000 the size of an atom. But now, researchers at MIT have found that neutrons can actually be made to cling to particles called quantum dots, which are made up of tens of thousands of atomic nuclei, held there just by the strong force.

The new finding may lead to useful new tools for probing the basic properties of materials at the quantum level, including those arising from the strong force, as well as exploring new kinds of quantum information processing devices. The work is reported this week in the journal ACS Nano, in a paper by MIT graduate students Hao Tang and Guoqing Wang and MIT professors Ju Li and Paola Cappellaro of the Department of Nuclear Science and Engineering.

Neutrons are widely used to probe material properties using a method called neutron scattering, in which a beam of neutrons is focused on a sample, and the neutrons that bounce off the material’s atoms can be detected to reveal the material’s internal structure and dynamics.

But until this new work, nobody thought that these neutrons might actually stick to the materials they were probing. “The fact that [the neutrons] can be trapped by the materials, nobody seems to know about that,” says Li, who is also a professor of materials science and engineering. “We were surprised that this exists, and that nobody had talked about it before, among the experts we had checked with,” he says.

The reason this new finding is so surprising, Li explains, is because neutrons don’t interact with electromagnetic forces. Of the four fundamental forces, gravity and the weak force “are generally not important for materials,” he says. “Pretty much everything is electromagnetic interaction, but in this case, since the neutron doesn’t have a charge, the interaction here is through the strong interaction, and we know that is very short-range. It is effective at a range of 10 to the minus 15 power,” or one quadrillionth, of a meter.

“It’s very small, but it’s very intense,” he says of this force that holds the nuclei of atoms together. “But what’s interesting is we’ve got these many thousands of nuclei in this neutronic quantum dot, and that’s able to stabilize these bound states, which have much more diffuse wavefunctions at tens of nanometers [billionths of a meter].  These neutronic bound states in a quantum dot are actually quite akin to Thomson’s plum pudding model of an atom, after his discovery of the electron.”

It was so unexpected, Li calls it “a pretty crazy solution to a quantum mechanical problem.” The team calls the newly discovered state an artificial “neutronic molecule.”

These neutronic molecules are made from quantum dots, which are tiny crystalline particles, collections of atoms so small that their properties are governed more by the exact size and shape of the particles than by their composition. The discovery and controlled production of quantum dots were the subject of the 2023 Nobel Prize in Chemistry, awarded to MIT Professor Moungi Bawendi and two others.

“In conventional quantum dots, an electron is trapped by the electromagnetic potential created by a macroscopic number of atoms, thus its wavefunction extends to about 10 nanometers, much larger than a typical atomic radius,” says Cappellaro. “Similarly, in these nucleonic quantum dots, a single neutron can be trapped by a nanocrystal, with a size well beyond the range of the nuclear force, and display similar quantized energies.” While these energy jumps give quantum dots their colors, the neutronic quantum dots could be used for storing quantum information.

This work is based on theoretical calculations and computational simulations. “We did it analytically in two different ways, and eventually also verified it numerically,” Li says. Although the effect had never been described before, he says, in principle there’s no reason it couldn’t have been found much sooner: “Conceptually, people should have already thought about it,” he says, but as far as the team has been able to determine, nobody did.

Part of the difficulty in doing the computations is the very different scales involved: The binding energy of a neutron to the quantum dots they were attaching to is about one-trillionth that of previously known conditions where the neutron is bound to a small group of nucleons. For this work, the team used an analytical tool called Green’s function to demonstrate that the strong force was sufficient to capture neutrons with a quantum dot with a minimum radius of 13 nanometers.

Then, the researchers did detailed simulations of specific cases, such as the use of a lithium hydride nanocrystal, a material being studied as a possible storage medium for hydrogen. They showed that the binding energy of the neutrons to the nanocrystal is dependent on the exact dimensions and shape of the crystal, as well as the nuclear spin polarizations of the nuclei compared to that of the neutron. They also calculated similar effects for thin films and wires of the material as opposed to particles.

But Li says that actually creating such neutronic molecules in the lab, which among other things requires specialized equipment to maintain temperatures in the range of a few thousandths of a Kelvin above absolute zero, is something that other researchers with the appropriate expertise will have to undertake.

Li notes that “artificial atoms” made up of assemblages of atoms that share properties and can behave in many ways like a single atom have been used to probe many properties of real atoms. Similarly, he says, these artificial molecules provide “an interesting model system” that might be used to study “interesting quantum mechanical problems that one can think about,” such as whether these neutronic molecules will have a shell structure that mimics the electron shell structure of atoms.

“One possible application,” he says, “is maybe we can precisely control the neutron state. By changing the way the quantum dot oscillates, maybe we can shoot the neutron off in a particular direction.” Neutrons are powerful tools for such things as triggering both fission and fusion reactions, but so far it has been difficult to control individual neutrons. These new bound states could provide much greater degrees of control over individual neutrons, which could play a role in the development of new quantum information systems, he says.

“One idea is to use it to manipulate the neutron, and then the neutron will be able to affect other nuclear spins,” Li says. In that sense, he says, the neutronic molecule could serve as a mediator between the nuclear spins of separate nuclei — and this nuclear spin is a property that is already being used as a basic storage unit, or qubit, in developing quantum computer systems.

“The nuclear spin is like a stationary qubit, and the neutron is like a flying qubit,” he says. “That’s one potential application.” He adds that this is “quite different from electromagnetics-based quantum information processing, which is so far the dominant paradigm. So, regardless of whether it’s superconducting qubits or it’s trapped ions or nitrogen vacancy centers, most of these are based on electromagnetic interactions.” In this new system, instead, “we have neutrons and nuclear spin. We’re just starting to explore what we can do with it now.”

Another possible application, he says, is for a kind of imaging, using neutral activation analysis. “Neutron imaging complements X-ray imaging because neutrons are much more strongly interacting with light elements,” Li says. It can also be used for materials analysis, which can provide information not only about elemental composition but even about the different isotopes of those elements. “A lot of the chemical imaging and spectroscopy doesn’t tell us about the isotopes,” whereas the neutron-based method could do so, he says.

The research was supported by the U.S. Office of Naval Research.

A new set of advanced nanofabrication equipment will make MIT.nano one of the world’s most advanced research facilities in microelectronics and related technologies, unlocking new opportunities for experimentation and widening the path for promising inventions to become impactful new products.

The equipment, provided by Applied Materials, will significantly expand MIT.nano’s nanofabrication capabilities, making them compatible with wafers — thin, round slices of semiconductor material — up to 200 millimeters, or 8 inches, in diameter, a size widely used in industry. The new tools will allow researchers to prototype a vast array of new microelectronic devices using state-of-the-art materials and fabrication processes. At the same time, the 200-millimeter compatibility will support close collaboration with industry and enable innovations to be rapidly adopted by companies and mass produced.

MIT.nano’s leaders say the equipment, which will also be available to scientists outside of MIT, will dramatically enhance their facility’s capabilities, allowing experts in the region to more efficiently explore new approaches in “tough tech” sectors, including advanced electronics, next-generation batteries, renewable energies, optical computing, biological sensing, and a host of other areas — many likely yet to be imagined.

“The toolsets will provide an accelerative boost to our ability to launch new technologies that can then be given to the world at scale,” says MIT.nano Director Vladimir Bulović, who is also the Fariborz Maseeh Professor of Emerging Technology. “MIT.nano is committed to its expansive mission — to build a better world. We provide toolsets and capabilities that, in the hands of brilliant researchers, can effectively move the world forward.”

The announcement comes as part of an agreement between MIT and Applied Materials, Inc. that, together with a grant to MIT from the Northeast Microelectronics Coalition (NEMC) Hub, commits more than $40 million of estimated private and public investment to add advanced nano-fabrication equipment and capabilities at MIT.nano.

“We don’t believe there is another space in the United States that will offer the same kind of versatility, capability, and accessibility, with 8-inch toolsets integrated right next to more fundamental toolsets for research discoveries,” Bulović says. “It will create a seamless path to accelerate the pace of innovation.”

Pushing the boundaries of innovation

Applied Materials is the world’s largest supplier of equipment for manufacturing semiconductors, displays, and other advanced electronics. The company will provide at MIT.nano several state-of-the-art process tools capable of supporting 150- and 200-millimeter wafers and will enhance and upgrade an existing tool owned by MIT. In addition to assisting MIT.nano in the day-to-day operation and maintenance of the equipment, Applied Materials engineers will develop new process capabilities to benefit researchers and students from MIT and beyond.

“This investment will significantly accelerate the pace of innovation and discovery in microelectronics and microsystems,” says Tomás Palacios, director of MIT’s Microsystems Technology Laboratories and the Clarence J. Lebel Professor in Electrical Engineering. “It’s wonderful news for our community, wonderful news for the state, and, in my view, a tremendous step forward toward implementing the national vision for the future of innovation in microelectronics.”

Nanoscale research at universities is traditionally conducted on machines that are less compatible with industry, which makes academic innovations more difficult to turn into impactful, mass-produced products. Jorg Scholvin, associate director for MIT.nano’s shared fabrication facility, says the new machines, when combined with MIT.nano’s existing equipment, represent a step-change improvement in that area: Researchers will be able to take an industry-standard wafer and build their technology on top of it to prove to companies it works on existing devices, or to co-fabricate new ideas in close collaboration with industry partners.

“In the journey from an idea to a fully working device, the ability to begin on a small scale, figure out what you want to do, rapidly debug your designs, and then scale it up to an industry-scale wafer is critical,” Scholvin says. “It means a student can test out their idea on wafer-scale quickly and directly incorporate insights into their project so that their processes are scalable. Providing such proof-of-principle early on will accelerate the idea out of the academic environment, potentially reducing years of added effort. Other tools at MIT.nano can supplement work on the 200-millimeter wafer scale, but the higher throughput and higher precision of the Applied equipment will provide researchers with repeatability and accuracy that is unprecedented for academic research environments. Essentially what you have is a sharper, faster, more precise tool to do your work.”

Scholvin predicts the equipment will lead to exponential growth in research opportunities.

“I think a key benefit of these tools is they allow us to push the boundary of research in a variety of different ways that we can predict today,” Scholvin says. “But then there are also unpredictable benefits, which are hiding in the shadows waiting to be discovered by the creativity of the researchers at MIT. With each new application, more ideas and paths usually come to mind — so that over time, more and more opportunities are discovered.”

Because the equipment is available for use by people outside of the MIT community, including regional researchers, industry partners, nonprofit organizations, and local startups, they will also enable new collaborations.

“The tools themselves will be an incredible meeting place — a place that can, I think, transpose the best of our ideas in a much more effective way than before,” Bulović says. “I’m extremely excited about that.”

Palacios notes that while microelectronics is best known for work making transistors smaller to fit on microprocessors, it’s a vast field that enables virtually all the technology around us, from wireless communications and high-speed internet to energy management, personalized health care, and more.

He says he’s personally excited to use the new machines to do research around power electronics and semiconductors, including exploring promising new materials like gallium nitride, which could dramatically improve the efficiency of electronic devices.

Fulfilling a mission

MIT.nano’s leaders say a key driver of commercialization will be startups, both from MIT and beyond.

“This is not only going to help the MIT research community innovate faster, it’s also going to enable a new wave of entrepreneurship,” Palacios says. “We’re reducing the barriers for students, faculty, and other entrepreneurs to be able to take innovation and get it to market. That fits nicely with MIT’s mission of making the world a better place through technology. I cannot wait to see the amazing new inventions that our colleagues and students will come out with.”

Bulović says the announcement aligns with the mission laid out by MIT’s leaders at MIT.nano’s inception.

"We have the space in MIT.nano to accommodate these tools, we have the capabilities inside MIT.nano to manage their operation, and as a shared and open facility, we have methodologies by which we can welcome anyone from the region to use the tools,” Bulović says. “That is the vision MIT laid out as we were designing MIT.nano, and this announcement helps to fulfill that vision.”

The Large Hadron Collider has transformed our understanding of physics since it began operating in 2008, enabling researchers to investigate the fundamental building blocks of the universe. Some 100 meters below the border between France and Switzerland, particles accelerate along the LHC’s 27-kilometer circumference, nearly reaching the speed of light before smashing together.

The LHC is often described as the biggest machine ever built. And while the physicists who carry out experiments at the facility tend to garner most of the attention, it takes hundreds of engineers and technicians to keep the LHC running. One such engineer is Irene Degl’Innocenti, who works in digital electronics at the European Organization for Nuclear Research (CERN), which operates the LHC. As a member of CERN’s beam instrumentation group, Degl’Innocenti creates custom electronics that measure the position of the particle beams as they travel.

Irene Degl’Innocenti

Employer:

CERN

Occupation:

Digital electronics engineer

Education:

Bachelor’s and master’s degrees in electrical engineering; Ph.D. in electrical, electronics, and communications engineering, University of Pisa, in Italy

“It’s a huge machine that does very challenging things, so the amount of expertise needed is vast,” Degl’Innocenti says.

The electronics she works on make up only a tiny part of the overall operation, something Degl’Innocenti is keenly aware of when she descends into the LHC’s cavernous tunnels to install or test her equipment. But she gets great satisfaction from working on such an important endeavor.

“You’re part of something that is very huge,” she says. “You feel part of this big community trying to understand what is actually going on in the universe, and that is very fascinating.”

Opportunities to Work in High-energy Physics

Growing up in Italy, Degl’Innocenti wanted to be a novelist. Throughout high school she leaned toward the humanities, but she had a natural affinity for math, thanks in part to her mother, who is a science teacher.

“I’m a very analytical person, and that has always been part of my mind-set, but I just didn’t find math charming when I was little,” Degl’Innocenti says. “It took a while to realize the opportunities it could open up.”

She started exploring electronics around age 17 because it seemed like the most direct way to translate her logical, mathematical way of thinking into a career. In 2011, she enrolled in the University of Pisa, in Italy, earning a bachelor’s degree in electrical engineering in 2014 and staying on to earn a master’s degree in the same subject.

At the time, Degl’Innocenti had no idea there were opportunities for engineers to work in high-energy physics. But she learned that a fellow student had attended a summer internship at Fermilab, the participle physics and accelerator laboratory in Batavia, Ill. So she applied for and won an internship there in 2015. Since Fermilab and CERN closely collaborate, she was able to help design a data-processing board for LHC’s Compact Muon Solenoid experiment.

Next she looked for an internship closer to home and discovered CERN’s technical student program, which allows students to work on a project over the course of a year. Working in the beam-instrumentation group, Degl’Innocenti designed a digital-acquisition system that became the basis for her master’s thesis.

Measuring the Position of Particle Beams

After receiving her master’s in 2017, Degl’Innocenti went on to pursue a Ph.D., also at the University of Pisa. She conducted her research at CERN’s beam-position section, which builds equipment to measure the position of particle beams within CERN’s accelerator complex. The LHC has roughly 1,000 monitors spaced around the accelerator ring. Each monitor typically consists of two pairs of sensors positioned on opposite sides of the accelerator pipe, and it is possible to measure the beam’s horizontal and vertical positions by comparing the strength of the signal at each sensor.

The underlying concept is simple, Degl’Innocenti says, but these measurements must be precise. Bunches of particles pass through the monitors every 25 nanoseconds, and their position must be tracked to within 50 micrometers.

“We start developing a system years in advance, and then it has to work for a couple of decades.”

Most of the signal processing is normally done in analog, but during her Ph.D., she focused on shifting as much of this work as possible to the digital domain because analog circuits are finicky, she says. They need to be precisely calibrated, and their accuracy tends to drift over time or when temperatures fluctuate.

“It’s complex to maintain,” she says. “It becomes particularly tricky when you have 1,000 monitors, and they are located in an accelerator 100 meters underground.”

Information is lost when analog is converted to digital, however, so Degl’Innocenti analyzed the performance of the latest analog-to-digital converters (ADCs) and investigated their effect on position measurements.

Designing Beam-Monitor Electronics

After completing her Ph.D. in electrical, electronics, and communications engineering in 2021, Degl’Innocenti joined CERN as a senior postdoctoral fellow. Two years later, she became a full-time employee there, applying the results of her research to developing new hardware. She’s currently designing a new beam-position monitor for the High-Luminosity upgrade to the LHC, expected to be completed in 2028. This new system will likely use a system-on-chip to house most of the electronics, including several ADCs and a field-programmable gate array (FPGA) that Degl’Innocenti will program to run a new digital signal-processing algorithm.

She’s part of a team of just 15 who handle design, implementation, and ongoing maintenance of CERN’s beam-position monitors. So she works closely with the engineers who design sensors and software for those instruments and the physicists who operate the accelerator and set the instruments’ requirements.

“We start developing a system years in advance, and then it has to work for a couple of decades,” Degl’Innocenti says.

Opportunities in High-Energy Physics

High-energy physics has a variety of interesting opportunities for engineers, Degl’Innocenti says, including high-precision electronics, vacuum systems, and cryogenics.

“The machines are very large and very complex, but we are looking at very small things,” she says. “There are a lot of big numbers involved both at the large scale and also when it comes to precision on the small scale.”

FPGA design skills are in high demand at all kinds of research facilities, and embedded systems are also becoming more important, Degl’Innocenti says. The key is keeping an open mind about where to apply your engineering knowledge, she says. She never thought there would be opportunities for people with her skill set at CERN.

“Always check what technologies are being used,” she advises. “Don’t limit yourself by assuming that working somewhere would not be possible.”

This article appears in the August 2024 print issue as “Irene Degl’Innocenti.”

I've been attempting to modify this example project https://github.com/keijiro/ComputeMarchingCubes

I'm trying to repurpose it to build terrain. After the Update() method in Assets/NoiseField/NoiseFieldVisualizer.cs I want to set a MeshCollider's sharedMesh to use the mesh that's been generated.

All I've done is add a line after the mesh is set:

GetComponent<MeshCollider>().sharedMesh = GetComponent<MeshFilter>().sharedMesh;

Currently I get an error:

Failed extracting collision mesh because vertex at index 2817 contains a non-finite value (0.000000, -nan, 1.000000). Mesh asset path "" Mesh name ""

When I iterate over sharedMesh.vertices and log them to console, I get either (0, 0, 0) or (-431602100.00, -431602100.00, -431602100.00) for each vertex value. Presumably because the values haven't been sent back to the CPU?

I have mesh cleaning enabled for the MeshCollider.

Is it possible to generate a mesh collider with a GPU-only mesh? Preferably without transferring the points back to the CPU.

I'm trying to implement the https://gafferongames.com/post/fix_your_timestep article but I have jitter on the position interpolation.

video of the problem

I have the following PhysX manager class update method :

 const float fixedTimeStep = 1.0f / 60.0f; // 60Hz
 float deltaTime = TimeManager::GetInstance()->DeltaTimeF();        
 if (deltaTime > 0.25f)
     deltaTime = 0.25f;
 accumulator += deltaTime;

 static std::unordered_map<PxRigidDynamic*, PhysXState> statesBefore{};
 static std::unordered_map<PxRigidDynamic*, PhysXState> statesAfter{};

 if (statesBefore.empty()) {
     RetrieveCurrentState(statesBefore);
     RetrieveCurrentState(statesAfter);
 }

 while (accumulator >= fixedTimeStep)
 {
     statesBefore = statesAfter;

     mScene->simulate(fixedTimeStep, nullptr, GSimulateScratchMemory, GSimulateScratchMemorySize);
     accumulator = std::max(accumulator - fixedTimeStep, 0.f);
     mScene->fetchResults(true);

     RetrieveCurrentState(statesAfter);
 }

 // Calculate the interpolation factor for rendering
 float alpha = accumulator / fixedTimeStep;

 for (const auto& [body, stateBefore] : statesBefore) {
     if (statesAfter.find(body) != statesAfter.end()) {
         const auto& stateAfter = statesAfter.at(body);
         PhysXState interpolatedState{};
         InterpolateStates(stateBefore, stateAfter, alpha, interpolatedState);

         // Update the interpolated state in the body userptr moveable body
         auto userPtr = static_cast<CollisionParam*>(body->userData);
         if (userPtr && userPtr->Body) {
             userPtr->Body->SetInterpolatedState(interpolatedState);
         }
     }
 } 

This is how I retrieve the current state:

void RetrieveCurrentState(std::unordered_map<PxRigidDynamic*, PhysXState>& states) {
    states.clear();
    for (auto rigidBody : mRigidBodies) {
        PhysXState state;

        physx::PxTransform transform = rigidBody->getGlobalPose();
        state.Position = glm::vec3(transform.p.x, transform.p.y, transform.p.z);
        state.Orientation = glm::quat(transform.q.w, transform.q.x, transform.q.y, transform.q.z);

        physx::PxVec3 linearVelocity = rigidBody->getLinearVelocity();
        state.Velocity = glm::vec3(linearVelocity.x, linearVelocity.y, linearVelocity.z);

        physx::PxVec3 angularVelocity = rigidBody->getAngularVelocity();
        state.AngularVelocity = glm::vec3(angularVelocity.x, angularVelocity.y, angularVelocity.z);

        states[rigidBody] = state;
    }
}

And here is how I interpolate:

void InterpolateStates(const PhysXState& previous, const PhysXState& current, float alpha, PhysXState& interpolated)
{
    interpolated.Position = glm::mix(previous.Position, current.Position, alpha);
    interpolated.Orientation = glm::slerp(previous.Orientation, current.Orientation, alpha);
    interpolated.Velocity = glm::mix(previous.Velocity, current.Velocity, alpha);
    interpolated.AngularVelocity = glm::mix(previous.AngularVelocity, current.AngularVelocity, alpha);
}

Finally here is how I retrieve the interpolated position (currently using only the position as a test phase) to feed it into the graphics module:

prop.Transform.setLocalPosition(prop.MoveableBody->GetInterpolatedPosition());

What could be wrong and the movement is shaky/jittery ? Let me know if you need to see more code.

The universe seems like it should be unfathomably complex. How then is science able to crack fundamental questions about nature and life? Scientists and philosophers alike have often commented on the “unreasonable” success of mathematics at describing the universe. That success has helped science probe some profound mysteries — but as the physicist Nigel Goldenfeld points out, it also helps that...

Source

We learn in grade school that water freezes at zero degrees Celsius, but that’s seldom true. In clouds, scientists have found supercooled water droplets as chilly as minus 40 C, and in a lab in 2014, they cooled water to a staggering minus 46 C before it froze. You can supercool water at home: Throw a bottle of distilled water in your freezer, and it’s unlikely to crystallize until you shake it.

Source

MIT faculty members Nancy Kanwisher, Robert Langer, and Sara Seager are among eight researchers worldwide to receive this year’s Kavli Prizes.

A partnership among the Norwegian Academy of Science and Letters, the Norwegian Ministry of Education and Research, and the Kavli Foundation, the Kavli Prizes are awarded every two years to “honor scientists for breakthroughs in astrophysics, nanoscience and neuroscience that transform our understanding of the big, the small and the complex.” The laureates in each field will share $1 million.

Understanding recognition of faces

Nancy Kanwisher, the Walter A Rosenblith Professor of Brain and Cognitive Sciences and McGovern Institute for Brain Research investigator, has been awarded the 2024 Kavli Prize in Neuroscience with Doris Tsao, professor in the Department of Molecular and Cell Biology at the University of California at Berkeley, and Winrich Freiwald, the Denise A. and Eugene W. Chinery Professor at the Rockefeller University.

Kanwisher, Tsao, and Freiwald discovered a specialized system within the brain to recognize faces. Their discoveries have provided basic principles of neural organization and made the starting point for further research on how the processing of visual information is integrated with other cognitive functions.

Kanwisher was the first to prove that a specific area in the human neocortex is dedicated to recognizing faces, now called the fusiform face area. Using functional magnetic resonance imaging, she found individual differences in the location of this area and devised an analysis technique to effectively localize specialized functional regions in the brain. This technique is now widely used and applied to domains beyond the face recognition system. 

Integrating nanomaterials for biomedical advances

Robert Langer, the David H. Koch Institute Professor, has been awarded the 2024 Kavli Prize in Nanoscience with Paul Alivisatos, president of the University of Chicago and John D. MacArthur Distinguished Service Professor in the Department of Chemistry, and Chad Mirkin, professor of chemistry at Northwestern University.

Langer, Alivisatos, and Mirkin each revolutionized the field of nanomedicine by demonstrating how engineering at the nano scale can advance biomedical research and application. Their discoveries contributed foundationally to the development of therapeutics, vaccines, bioimaging, and diagnostics.

Langer was the first to develop nanoengineered materials that enabled the controlled release, or regular flow, of drug molecules. This capability has had an immense impact for the treatment of a range of diseases, such as aggressive brain cancer, prostate cancer, and schizophrenia. His work also showed that tiny particles, containing protein antigens, can be used in vaccination, and was instrumental in the development of the delivery of messenger RNA vaccines. 

Searching for life beyond Earth

Sara Seager, the Class of 1941 Professor of Planetary Sciences in the Department of Earth, Atmospheric and Planetary Sciences and a professor in the departments of Physics and of Aeronautics and Astronautics, has been awarded the 2024 Kavli Prize in Astrophysics along with David Charbonneau, the Fred Kavli Professor of Astrophysics at Harvard University.

Seager and Charbonneau are recognized for discoveries of exoplanets and the characterization of their atmospheres. They pioneered methods for the detection of atomic species in planetary atmospheres and the measurement of their thermal infrared emission, setting the stage for finding the molecular fingerprints of atmospheres around both giant and rocky planets. Their contributions have been key to the enormous progress seen in the last 20 years in the exploration of myriad exoplanets. 

Kanwisher, Langer, and Seager bring the number of all-time MIT faculty recipients of the Kavli Prize to eight. Prior winners include Rainer Weiss in astrophysics (2016), Alan Guth in astrophysics (2014), Mildred Dresselhaus in nanoscience (2012), Ann Graybiel in neuroscience (2012), and Jane Luu in astrophysics (2012).

MIT physicists and colleagues have created a five-lane superhighway for electrons that could allow ultra-efficient electronics and more. 

The work, reported in the May 10 issue of Science, is one of several important discoveries by the same team over the past year involving a material that is a unique form of graphene.

“This discovery has direct implications for low-power electronic devices because no energy is lost during the propagation of electrons, which is not the case in regular materials where the electrons are scattered,” says Long Ju, an assistant professor in the Department of Physics and corresponding author of the Science paper.

The phenomenon is akin to cars traveling down an open turnpike as opposed to those moving through neighborhoods. The neighborhood cars can be stopped or slowed by other drivers making abrupt stops or U-turns that disrupt an otherwise smooth commute.

A new material

The material behind this work, known as rhombohedral pentalayer graphene, was discovered two years ago by physicists led by Ju. “We found a goldmine, and every scoop is revealing something new,” says Ju, who is also affiliated with MIT’s Materials Research Laboratory.

In a Nature Nanotechnology paper last October, Ju and colleagues reported the discovery of three important properties arising from rhombohedral graphene. For example, they showed that it could be topological, or allow the unimpeded movement of electrons around the edge of the material but not through the middle. That resulted in a superhighway, but required the application of a large magnetic field some tens of thousands times stronger than the Earth’s magnetic field.

In the current work, the team reports creating the superhighway without any magnetic field.

Tonghang Han, an MIT graduate student in physics, is a co-first author of the paper. “We are not the first to discover this general phenomenon, but we did so in a very different system. And compared to previous systems, ours is simpler and also supports more electron channels.” Explains Ju, “other materials can only support one lane of traffic on the edge of the material. We suddenly bumped it up to five.”

Additional co-first authors of the paper who contributed equally to the work are Zhengguang Lu and Yuxuan Yao. Lu is a postdoc in the Materials Research Laboratory. Yao conducted the work as a visiting undergraduate student from Tsinghua University. Other authors are MIT professor of physics Liang Fu; Jixiang Yang and Junseok Seo, both MIT graduate students in physics; Chiho Yoon and Fan Zhang of the University of Texas at Dallas; and Kenji Watanabe and Takashi Taniguchi of the National Institute for Materials Science in Japan.

How it works

Graphite, the primary component of pencil lead, is composed of many layers of graphene, a single layer of carbon atoms arranged in hexagons resembling a honeycomb structure. Rhombohedral graphene is composed of five layers of graphene stacked in a specific overlapping order.

Ju and colleagues isolated rhombohedral graphene thanks to a novel microscope Ju built at MIT in 2021 that can quickly and relatively inexpensively determine a variety of important characteristics of a material at the nanoscale. Pentalayer rhombohedral stacked graphene is only a few billionths of a meter thick.

In the current work, the team tinkered with the original system, adding a layer of tungsten disulfide (WS₂). “The interaction between the WS₂ and the pentalayer rhombohedral graphene resulted in this five-lane superhighway that operates at zero magnetic field,” says Ju.

Comparison to superconductivity

The phenomenon that the Ju group discovered in rhombohedral graphene that allows electrons to travel with no resistance at zero magnetic field is known as the quantum anomalous Hall effect. Most people are more familiar with superconductivity, a completely different phenomenon that does the same thing but happens in very different materials.

Ju notes that although superconductors were discovered in the 1910s, it took some 100 years of research to coax the system to work at the higher temperatures necessary for applications. “And the world record is still well below room temperature,” he notes.

Similarly, the rhombohedral graphene superhighway currently operates at about 2 kelvins, or -456 degrees Fahrenheit. “It will take a lot of effort to elevate the temperature, but as physicists, our job is to provide the insight; a different way for realizing this [phenomenon],” Ju says.

Very exciting

The discoveries involving rhombohedral graphene came as a result of painstaking research that wasn’t guaranteed to work. “We tried many recipes over many months,” says Han, “so it was very exciting when we cooled the system to a very low temperature and [a five-lane superhighway operating at zero magnetic field] just popped out.”

Says Ju, “it’s very exciting to be the first to discover a phenomenon in a new system, especially in a material that we uncovered.”

This work was supported by a Sloan Fellowship; the U.S. National Science Foundation; the U.S. Office of the Under Secretary of Defense for Research and Engineering; the Japan Society for the Promotion of Science KAKENHI; and the World Premier International Research Initiative of Japan.

Physics graduate student Jeong Min (Jane) Park is among the 32 exceptional early-career scientists worldwide chosen to receive the prestigious 2024 Schmidt Science Fellows award.  

As a 2024 Schmidt Science Fellow, Park’s postdoctoral work will seek to directly detect phases that could host new particles by employing an instrument that can visualize subatomic-scale phenomena.  

With her advisor, Pablo Jarillo-Herrero, the Cecil and Ida Green Professor of Physics, Park’s research at MIT focuses on discovering novel quantum phases of matter.

“When there are many electrons in a material, their interactions can lead to collective behaviors that are not expected from individual particles, known as emergent phenomena,” explains Park. “One example is superconductivity, where interacting electrons combine together as a pair at low temperatures to conduct electricity without energy loss.”

During her PhD studies, she has investigated novel types of superconductivity by designing new materials with targeted interactions and topology. In particular, she used graphene, atomically thin two-dimensional layers of graphite, the same material as pencil lead, and turned it into a “magic” material. This so-called magic-angle twisted trilayer graphene provided an extraordinarily strong form of superconductivity that is robust under high magnetic fields. Later, she found a whole “magic family” of these materials, elucidating the key mechanisms behind superconductivity and interaction-driven phenomena. These results have provided a new platform to study emergent phenomena in two dimensions, which can lead to innovations in electronics and quantum technology.

Park says she is looking forward to her postdoctoral studies with Princeton University physics professor Ali Yazdani's lab.

“I’m excited about the idea of discovering and studying new quantum phenomena that could further the understanding of fundamental physics,” says Park. “Having explored interaction-driven phenomena through the design of new materials, I’m now aiming to broaden my perspective and expertise to address a different kind of question, by combining my background in material design with the sophisticated local-scale measurements that I will adopt during my postdoc.”

She explains that elementary particles are classified as either bosons or fermions, with contrasting behaviors upon interchanging two identical particles, referred to as exchange statistics; bosons remain unchanged, while fermions acquire a minus sign in their quantum wavefunction.

Theories predict the existence of fundamentally different particles known as non-abelian anyons, whose wavefunctions braid upon particle exchange. Such a braiding process can be used to encode and store information, potentially opening the door to fault-tolerant quantum computing in the future.

Since 2018, this prestigious postdoctoral program has sought to break down silos among scientific fields to solve the world’s biggest challenges and support future leaders in STEM.

Schmidt Science Fellows, an initiative of Schmidt Sciences, delivered in partnership with the Rhodes Trust, identifies, develops, and amplifies the next generation of science leaders, by building a community of scientists and supporters of interdisciplinary science and leveraging this network to drive sector-wide change. The 2024 fellows consist of 17 nationalities across North America, Europe, and Asia.   

Nominated candidates undergo a rigorous selection process that includes a paper-based academic review with panels of experts in their home disciplines and final interviews with panels, including senior representatives from across many scientific disciplines and different business sectors.  

John Joannopoulos, an innovator and mentor in the fields of theoretical condensed matter physics and nanophotonics, has been named the recipient of the 2024-2025 James R. Killian Jr. Faculty Achievement Award.

Joannopoulos is the Francis Wright Davis Professor of Physics and director of MIT’s Institute for Soldier Nanotechnologies. He has been a member of the MIT faculty for 50 years.

“Professor Joannopoulos’s profound and lasting impact on the field of theoretical condensed matter physics finds its roots in his pioneering work in harnessing ab initio physics to elucidate the behavior of materials at the atomic level,” states the award citation, which was announced at today’s faculty meeting by Roger White, chair of the Killian Award Selection Committee and professor of philosophy at MIT. “His seminal research in the development of photonic crystals has revolutionized understanding of light-matter interactions, laying the groundwork for transformative advancements in diverse fields ranging from telecommunications to biomedical engineering.”

The award also honors Joannopoulos’ service as a “legendary mentor to generations of students, inspiring them to achieve excellence in science while at the same time facilitating the practical benefit to society through entrepreneurship.”

The Killian Award was established in 1971 to recognize outstanding professional contributions by MIT faculty members. It is the highest honor that the faculty can give to one of its members.

“I have to tell you, it was a complete and utter surprise,” Joannopoulos told MIT News shortly after he received word of the award. “I didn’t expect it at all, and was extremely flattered, honored, and moved by it, frankly.”

Joannopoulous has spent his entire professional career at MIT. He came to the Institute in 1974, directly after receiving his PhD in physics at the University of California at Berkeley, where he also earned his bachelor’s degree. Starting out as an assistant professor in MIT’s Department of Physics, he quickly set up a research program focused on theoretical condensed matter physics.

Over the first half of his MIT career, Joannopoulos worked to elucidate the fundamental nature of the electronic, vibrational, and optical structure of crystalline and amorphous bulk solids, their surfaces, interfaces, and defects. He and his students developed numerous theoretical methods to enable tractable and accurate calculations of these complex systems.

In the 1990s, his work with microscopic material systems expanded to a new class of materials, called photonic crystals — materials that could be engineered at the micro- and nanoscale to manipulate light in ways that impart surprising and exotic optical qualities to the material as a whole.

“I saw that you could create photonic crystals with defects that can affect the properties of photons, in much the same way that defects in a semiconductor affect the properties of electrons,” Joannopoulos says. “So I started working in this area to try and explore what anomalous light phenomena can we discover using this approach?”

Among his various breakthroughs in the field was the realization of a “perfect dielectric mirror” — a multilayered optical device that reflects light from all angles as normal metallic mirrors do, and that can also be tuned to reflect and trap light at specific frequencies. He and his colleagues saw potential for the mirror to be made into a hollow fiber that could serve as a highly effective optical conduit, for use in a wide range of applications. To further advance the technology, he and his colleagues launched a startup, which has since developed the technology into a flexible, fiber-optic “surgical scalpel.”

Throughout his career, Joannopoulos has helped to launch numerous startups and photonics-based technologies.

“His ability to bridge the gap between academia and industry has not only advanced scientific knowledge but also led to the creation of dozens of new companies, thousands of jobs, and groundbreaking products that continue to benefit society to this day,” the award citation states.

In 2006, Joannopoulos accepted the position as director of MIT’s Institute for Soldier Nanotechnologies (ISN), a collaboration between MIT researchers, industry partners, and military defense experts, who seek innovations to protect and enhance soldiers’ survivability in the field. In his role as ISN head, Joannopoulos has worked across MIT, making connections and supporting new projects with researchers specializing in fields far from his own.

“I get a chance to explore and learn fascinating new things,” says Joannopoulos, who is currently overseeing projects related to hyperspectral imaging, smart and responsive fabrics, and nanodrug delivery. “I love that aspect of really getting to understand what people in other fields are doing. And they’re doing great work across many, many different fields.”

Throughout his career at MIT, Joannopoulos has been especially inspired and motivated by his students, many of whom have gone on to found companies, lead top academic and research institutions, and make significant contributions to their respective fields, including one student who was awarded the Nobel Prize in Physics in 1998.

“One’s proudest moments are the successes of one’s students, and in that regard, I’ve been extremely lucky to have had truly exceptional students over the years,” Joannopolous says.

His many contributions to academia and industry have earned Joannopoulos numerous honors and awards, including his election to both the National Academy of Sciences and the American Academy of Arts and Sciences. He is also a fellow of both the American Physical Society and the American Association for the Advancement of Science.

“The Selection Committee is delighted to have this opportunity to honor Professor John Joannopoulos: a visionary scientist, a beloved mentor, a great believer in the goodness of people, and a leader whose contributions to MIT and the broader scientific community are immeasurable,” the award citation concludes.

Proximity is key for many quantum phenomena, as interactions between atoms are stronger when the particles are close. In many quantum simulators, scientists arrange atoms as close together as possible to explore exotic states of matter and build new quantum materials.

They typically do this by cooling the atoms to a stand-still, then using laser light to position the particles as close as 500 nanometers apart — a limit that is set by the wavelength of light. Now, MIT physicists have developed a technique that allows them to arrange atoms in much closer proximity, down to a mere 50 nanometers. For context, a red blood cell is about 1,000 nanometers wide.

The physicists demonstrated the new approach in experiments with dysprosium, which is the most magnetic atom in nature. They used the new approach to manipulate two layers of dysprosium atoms, and positioned the layers precisely 50 nanometers apart. At this extreme proximity, the magnetic interactions were 1,000 times stronger than if the layers were separated by 500 nanometers.

What’s more, the scientists were able to measure two new effects caused by the atoms’ proximity. Their enhanced magnetic forces caused “thermalization,” or the transfer of heat from one layer to another, as well as synchronized oscillations between layers. These effects petered out as the layers were spaced farther apart.

“We have gone from positioning atoms from 500 nanometers to 50 nanometers apart, and there is a lot you can do with this,” says Wolfgang Ketterle, the John D. MacArthur Professor of Physics at MIT. “At 50 nanometers, the behavior of atoms is so much different that we’re really entering a new regime here.”

Ketterle and his colleagues say the new approach can be applied to many other atoms to study quantum phenomena. For their part, the group plans to use the technique to manipulate atoms into configurations that could generate the first purely magnetic quantum gate — a key building block for a new type of quantum computer.

The team has published their results today in the journal Science. The study’s co-authors include lead author and physics graduate student Li Du, along with Pierre Barral, Michael Cantara, Julius de Hond, and Yu-Kun Lu — all members of the MIT-Harvard Center for Ultracold Atoms, the Department of Physics, and the Research Laboratory of Electronics at MIT.

Peaks and valleys

To manipulate and arrange atoms, physicists typically first cool a cloud of atoms to temperatures approaching absolute zero, then use a system of laser beams to corral the atoms into an optical trap.

Laser light is an electromagnetic wave with a specific wavelength (the distance between maxima of the electric field) and frequency. The wavelength limits the smallest pattern into which light can be shaped to typically 500 nanometers, the so-called optical resolution limit. Since atoms are attracted by laser light of certain frequencies, atoms will be positioned at the points of peak laser intensity. For this reason, existing techniques have been limited in how close they can position atomic particles, and could not be used to explore phenomena that happen at much shorter distances.

“Conventional techniques stop at 500 nanometers, limited not by the atoms but by the wavelength of light,” Ketterle explains. “We have found now a new trick with light where we can break through that limit.”

The team’s new approach, like current techniques, starts by cooling a cloud of atoms — in this case, to about 1 microkelvin, just a hair above absolute zero — at which point, the atoms come to a near-standstill. Physicists can then use lasers to move the frozen particles into desired configurations.

Then, Du and his collaborators worked with two laser beams, each with a different frequency, or color, and circular polarization, or direction of the laser’s electric field. When the two beams travel through a super-cooled cloud of atoms, the atoms can orient their spin in opposite directions, following either of the two lasers’ polarization. The result is that the beams produce two groups of the same atoms, only with opposite spins.

Each laser beam formed a standing wave, a periodic pattern of electric field intensity with a spatial period of 500 nanometers. Due to their different polarizations, each standing wave attracted and corralled one of two groups of atoms, depending on their spin. The lasers could be overlaid and tuned such that the distance between their respective peaks is as small as 50 nanometers, meaning that the atoms gravitating to each respective laser’s peaks would be separated by the same 50 nanometers.

But in order for this to happen, the lasers would have to be extremely stable and immune to all external noise, such as from shaking or even breathing on the experiment. The team realized they could stabilize both lasers by directing them through an optical fiber, which served to lock the light beams in place in relation to each other.

“The idea of sending both beams through the optical fiber meant the whole machine could shake violently, but the two laser beams stayed absolutely stable with respect to each others,” Du says.

Magnetic forces at close range

As a first test of their new technique, the team used atoms of dysprosium — a rare-earth metal that is one of the strongest magnetic elements in the periodic table, particularly at ultracold temperatures. However, at the scale of atoms, the element’s magnetic interactions are relatively weak at distances of even 500 nanometers. As with common refrigerator magnets, the magnetic attraction between atoms increases with proximity, and the scientists suspected that if their new technique could space dysprosium atoms as close as 50 nanometers apart, they might observe the emergence of otherwise weak interactions between the magnetic atoms.

“We could suddenly have magnetic interactions, which used to be almost neglible but now are really strong,” Ketterle says.

The team applied their technique to dysprosium, first super-cooling the atoms, then passing two lasers through to split the atoms into two spin groups, or layers. They then directed the lasers through an optical fiber to stabilize them, and found that indeed, the two layers of dysprosium atoms gravitated to their respective laser peaks, which in effect separated the layers of atoms by 50 nanometers — the closest distance that any ultracold atom experiment has been able to achieve.

At this extremely close proximity, the atoms’ natural magnetic interactions were significantly enhanced, and were 1,000 times stronger than if they were positioned 500 nanometers apart. The team observed that these interactions resulted in two novel quantum phenomena: collective oscillation, in which one layer’s vibrations caused the other layer to vibrate in sync; and thermalization, in which one layer transferred heat to the other, purely through magnetic fluctuations in the atoms.

“Until now, heat between atoms could only by exchanged when they were in the same physical space and could collide,” Du notes. “Now we have seen atomic layers, separated by vacuum, and they exchange heat via fluctuating magnetic fields.”

The team’s results introduce a new technique that can be used to position many types of atom in close proximity. They also show that atoms, placed close enough together, can exhibit interesting quantum phenomena, that could be harnessed to build new quantum materials, and potentially, magnetically-driven atomic systems for quantum computers.

“We are really bringing super-resolution methods to the field, and it will become a general tool for doing quantum simulations,” Ketterle says. “There are many variants possible, which we are working on.”

This research was funded, in part, by the National Science Foundation and the Department of Defense.

Neutrons are subatomic particles that have no electric charge, unlike protons and electrons. That means that while the electromagnetic force is responsible for most of the interactions between radiation and materials, neutrons are essentially immune to that force.

Instead, neutrons are held together inside an atom’s nucleus solely by something called the strong force, one of the four fundamental forces of nature. As its name implies, the force is indeed very strong, but only at very close range — it drops off so rapidly as to be negligible beyond 1/10,000 the size of an atom. But now, researchers at MIT have found that neutrons can actually be made to cling to particles called quantum dots, which are made up of tens of thousands of atomic nuclei, held there just by the strong force.

The new finding may lead to useful new tools for probing the basic properties of materials at the quantum level, including those arising from the strong force, as well as exploring new kinds of quantum information processing devices. The work is reported this week in the journal ACS Nano, in a paper by MIT graduate students Hao Tang and Guoqing Wang and MIT professors Ju Li and Paola Cappellaro of the Department of Nuclear Science and Engineering.

Neutrons are widely used to probe material properties using a method called neutron scattering, in which a beam of neutrons is focused on a sample, and the neutrons that bounce off the material’s atoms can be detected to reveal the material’s internal structure and dynamics.

But until this new work, nobody thought that these neutrons might actually stick to the materials they were probing. “The fact that [the neutrons] can be trapped by the materials, nobody seems to know about that,” says Li, who is also a professor of materials science and engineering. “We were surprised that this exists, and that nobody had talked about it before, among the experts we had checked with,” he says.

The reason this new finding is so surprising, Li explains, is because neutrons don’t interact with electromagnetic forces. Of the four fundamental forces, gravity and the weak force “are generally not important for materials,” he says. “Pretty much everything is electromagnetic interaction, but in this case, since the neutron doesn’t have a charge, the interaction here is through the strong interaction, and we know that is very short-range. It is effective at a range of 10 to the minus 15 power,” or one quadrillionth, of a meter.

“It’s very small, but it’s very intense,” he says of this force that holds the nuclei of atoms together. “But what’s interesting is we’ve got these many thousands of nuclei in this neutronic quantum dot, and that’s able to stabilize these bound states, which have much more diffuse wavefunctions at tens of nanometers [billionths of a meter].  These neutronic bound states in a quantum dot are actually quite akin to Thomson’s plum pudding model of an atom, after his discovery of the electron.”

It was so unexpected, Li calls it “a pretty crazy solution to a quantum mechanical problem.” The team calls the newly discovered state an artificial “neutronic molecule.”

These neutronic molecules are made from quantum dots, which are tiny crystalline particles, collections of atoms so small that their properties are governed more by the exact size and shape of the particles than by their composition. The discovery and controlled production of quantum dots were the subject of the 2023 Nobel Prize in Chemistry, awarded to MIT Professor Moungi Bawendi and two others.

“In conventional quantum dots, an electron is trapped by the electromagnetic potential created by a macroscopic number of atoms, thus its wavefunction extends to about 10 nanometers, much larger than a typical atomic radius,” says Cappellaro. “Similarly, in these nucleonic quantum dots, a single neutron can be trapped by a nanocrystal, with a size well beyond the range of the nuclear force, and display similar quantized energies.” While these energy jumps give quantum dots their colors, the neutronic quantum dots could be used for storing quantum information.

This work is based on theoretical calculations and computational simulations. “We did it analytically in two different ways, and eventually also verified it numerically,” Li says. Although the effect had never been described before, he says, in principle there’s no reason it couldn’t have been found much sooner: “Conceptually, people should have already thought about it,” he says, but as far as the team has been able to determine, nobody did.

Part of the difficulty in doing the computations is the very different scales involved: The binding energy of a neutron to the quantum dots they were attaching to is about one-trillionth that of previously known conditions where the neutron is bound to a small group of nucleons. For this work, the team used an analytical tool called Green’s function to demonstrate that the strong force was sufficient to capture neutrons with a quantum dot with a minimum radius of 13 nanometers.

Then, the researchers did detailed simulations of specific cases, such as the use of a lithium hydride nanocrystal, a material being studied as a possible storage medium for hydrogen. They showed that the binding energy of the neutrons to the nanocrystal is dependent on the exact dimensions and shape of the crystal, as well as the nuclear spin polarizations of the nuclei compared to that of the neutron. They also calculated similar effects for thin films and wires of the material as opposed to particles.

But Li says that actually creating such neutronic molecules in the lab, which among other things requires specialized equipment to maintain temperatures in the range of a few thousandths of a Kelvin above absolute zero, is something that other researchers with the appropriate expertise will have to undertake.

Li notes that “artificial atoms” made up of assemblages of atoms that share properties and can behave in many ways like a single atom have been used to probe many properties of real atoms. Similarly, he says, these artificial molecules provide “an interesting model system” that might be used to study “interesting quantum mechanical problems that one can think about,” such as whether these neutronic molecules will have a shell structure that mimics the electron shell structure of atoms.

“One possible application,” he says, “is maybe we can precisely control the neutron state. By changing the way the quantum dot oscillates, maybe we can shoot the neutron off in a particular direction.” Neutrons are powerful tools for such things as triggering both fission and fusion reactions, but so far it has been difficult to control individual neutrons. These new bound states could provide much greater degrees of control over individual neutrons, which could play a role in the development of new quantum information systems, he says.

“One idea is to use it to manipulate the neutron, and then the neutron will be able to affect other nuclear spins,” Li says. In that sense, he says, the neutronic molecule could serve as a mediator between the nuclear spins of separate nuclei — and this nuclear spin is a property that is already being used as a basic storage unit, or qubit, in developing quantum computer systems.

“The nuclear spin is like a stationary qubit, and the neutron is like a flying qubit,” he says. “That’s one potential application.” He adds that this is “quite different from electromagnetics-based quantum information processing, which is so far the dominant paradigm. So, regardless of whether it’s superconducting qubits or it’s trapped ions or nitrogen vacancy centers, most of these are based on electromagnetic interactions.” In this new system, instead, “we have neutrons and nuclear spin. We’re just starting to explore what we can do with it now.”

Another possible application, he says, is for a kind of imaging, using neutral activation analysis. “Neutron imaging complements X-ray imaging because neutrons are much more strongly interacting with light elements,” Li says. It can also be used for materials analysis, which can provide information not only about elemental composition but even about the different isotopes of those elements. “A lot of the chemical imaging and spectroscopy doesn’t tell us about the isotopes,” whereas the neutron-based method could do so, he says.

The research was supported by the U.S. Office of Naval Research.

A new set of advanced nanofabrication equipment will make MIT.nano one of the world’s most advanced research facilities in microelectronics and related technologies, unlocking new opportunities for experimentation and widening the path for promising inventions to become impactful new products.

The equipment, provided by Applied Materials, will significantly expand MIT.nano’s nanofabrication capabilities, making them compatible with wafers — thin, round slices of semiconductor material — up to 200 millimeters, or 8 inches, in diameter, a size widely used in industry. The new tools will allow researchers to prototype a vast array of new microelectronic devices using state-of-the-art materials and fabrication processes. At the same time, the 200-millimeter compatibility will support close collaboration with industry and enable innovations to be rapidly adopted by companies and mass produced.

MIT.nano’s leaders say the equipment, which will also be available to scientists outside of MIT, will dramatically enhance their facility’s capabilities, allowing experts in the region to more efficiently explore new approaches in “tough tech” sectors, including advanced electronics, next-generation batteries, renewable energies, optical computing, biological sensing, and a host of other areas — many likely yet to be imagined.

“The toolsets will provide an accelerative boost to our ability to launch new technologies that can then be given to the world at scale,” says MIT.nano Director Vladimir Bulović, who is also the Fariborz Maseeh Professor of Emerging Technology. “MIT.nano is committed to its expansive mission — to build a better world. We provide toolsets and capabilities that, in the hands of brilliant researchers, can effectively move the world forward.”

The announcement comes as part of an agreement between MIT and Applied Materials, Inc. that, together with a grant to MIT from the Northeast Microelectronics Coalition (NEMC) Hub, commits more than $40 million of estimated private and public investment to add advanced nano-fabrication equipment and capabilities at MIT.nano.

“We don’t believe there is another space in the United States that will offer the same kind of versatility, capability, and accessibility, with 8-inch toolsets integrated right next to more fundamental toolsets for research discoveries,” Bulović says. “It will create a seamless path to accelerate the pace of innovation.”

Pushing the boundaries of innovation

Applied Materials is the world’s largest supplier of equipment for manufacturing semiconductors, displays, and other advanced electronics. The company will provide at MIT.nano several state-of-the-art process tools capable of supporting 150- and 200-millimeter wafers and will enhance and upgrade an existing tool owned by MIT. In addition to assisting MIT.nano in the day-to-day operation and maintenance of the equipment, Applied Materials engineers will develop new process capabilities to benefit researchers and students from MIT and beyond.

“This investment will significantly accelerate the pace of innovation and discovery in microelectronics and microsystems,” says Tomás Palacios, director of MIT’s Microsystems Technology Laboratories and the Clarence J. Lebel Professor in Electrical Engineering. “It’s wonderful news for our community, wonderful news for the state, and, in my view, a tremendous step forward toward implementing the national vision for the future of innovation in microelectronics.”

Nanoscale research at universities is traditionally conducted on machines that are less compatible with industry, which makes academic innovations more difficult to turn into impactful, mass-produced products. Jorg Scholvin, associate director for MIT.nano’s shared fabrication facility, says the new machines, when combined with MIT.nano’s existing equipment, represent a step-change improvement in that area: Researchers will be able to take an industry-standard wafer and build their technology on top of it to prove to companies it works on existing devices, or to co-fabricate new ideas in close collaboration with industry partners.

“In the journey from an idea to a fully working device, the ability to begin on a small scale, figure out what you want to do, rapidly debug your designs, and then scale it up to an industry-scale wafer is critical,” Scholvin says. “It means a student can test out their idea on wafer-scale quickly and directly incorporate insights into their project so that their processes are scalable. Providing such proof-of-principle early on will accelerate the idea out of the academic environment, potentially reducing years of added effort. Other tools at MIT.nano can supplement work on the 200-millimeter wafer scale, but the higher throughput and higher precision of the Applied equipment will provide researchers with repeatability and accuracy that is unprecedented for academic research environments. Essentially what you have is a sharper, faster, more precise tool to do your work.”

Scholvin predicts the equipment will lead to exponential growth in research opportunities.

“I think a key benefit of these tools is they allow us to push the boundary of research in a variety of different ways that we can predict today,” Scholvin says. “But then there are also unpredictable benefits, which are hiding in the shadows waiting to be discovered by the creativity of the researchers at MIT. With each new application, more ideas and paths usually come to mind — so that over time, more and more opportunities are discovered.”

Because the equipment is available for use by people outside of the MIT community, including regional researchers, industry partners, nonprofit organizations, and local startups, they will also enable new collaborations.

“The tools themselves will be an incredible meeting place — a place that can, I think, transpose the best of our ideas in a much more effective way than before,” Bulović says. “I’m extremely excited about that.”

Palacios notes that while microelectronics is best known for work making transistors smaller to fit on microprocessors, it’s a vast field that enables virtually all the technology around us, from wireless communications and high-speed internet to energy management, personalized health care, and more.

He says he’s personally excited to use the new machines to do research around power electronics and semiconductors, including exploring promising new materials like gallium nitride, which could dramatically improve the efficiency of electronic devices.

Fulfilling a mission

MIT.nano’s leaders say a key driver of commercialization will be startups, both from MIT and beyond.

“This is not only going to help the MIT research community innovate faster, it’s also going to enable a new wave of entrepreneurship,” Palacios says. “We’re reducing the barriers for students, faculty, and other entrepreneurs to be able to take innovation and get it to market. That fits nicely with MIT’s mission of making the world a better place through technology. I cannot wait to see the amazing new inventions that our colleagues and students will come out with.”

Bulović says the announcement aligns with the mission laid out by MIT’s leaders at MIT.nano’s inception.

"We have the space in MIT.nano to accommodate these tools, we have the capabilities inside MIT.nano to manage their operation, and as a shared and open facility, we have methodologies by which we can welcome anyone from the region to use the tools,” Bulović says. “That is the vision MIT laid out as we were designing MIT.nano, and this announcement helps to fulfill that vision.”

I am confused about the usage of static / not simulated rigidbodies.

I get that it is better to disable simulated to temporarily stop a rigidbody rather than deleting and recreating it, especially because all references wont get destroyed, but why are there two options to stop it? What is the difference between a static rigidbody and a not simulated rigidbody?

Also I have heard that peoplre create a lot of colliders with static/not simulated colliders. Why bother to create rigidbodies at all if the gameObject is never meant to move? Doesn't this just waste processing power to a thing that is completely unnecessary?

What I need assistance with:

• I need to create a rope connecting two GameObjects together at runtime through code.

• One end will be connected to Transform _pointA and the other will be connected to Transform _pointB.

• I've divided the rope up into segments of GameObjects that have a Hinge joint 2D & a Rigidbody 2D.

• Each segment uses it's parent's Rigidbody 2D as the Connected Rigid Body.

• Then I set positions on the LineRenderer to match the segment positions so that I can later use rope material to make it looks nicer.

Issue:

• When the rope is initially created, it immediately falls straight down creating a vertical rope rather than a horizontal rope, even though the final rope segment is positioned at _pointB with the correct parent's Rigidbody connected.
• After a few moments, the rope falls apart without moving any positions manually.
• Additionally, if the rope is manually moved, it immediately falls apart.
• To demonstrate the issue, I added a circle sprite to each segment GameObject in the rope.

• Which causes the line to look like this:

Here's an example of how I would like it to look when moving the two objects further/closer:

The Code I'm Using:

public class Rope: MonoBehaviour
{

    [SerializeField] private LineRenderer _line;
    [SerializeField, Range(2, 50)] int _segmentCount = 2;

    [SerializeField] private Transform _pointA;
    [SerializeField] private Transform _pointB;

    [SerializeField] HingeJoint2D _hingeJoint;

    public Transform[] segments;
    private void Start()
    {
        GenerateRope();
    }
    // Update is called once per frame
    void Update()
    {
        SetEndOfRopePositions();
        SetLinePoints();
    }

    private void SetEndOfRopePositions()
    {
        segments[0].position = _pointA.position;
        segments[segments.Length - 1].position = _pointB.position;
    }

    private void SetLinePoints()
    {
        _line.positionCount = segments.Length;

        for (int i = 0; i < segments.Length; i++)
        {
            _line.SetPosition(i, segments[i].position);
        }
    }
    private Vector2 GetSegmentPosition(int segmentIndex)
    {
        Vector2 posA = _pointA.position;
        Vector2 posB = _pointB.position;

        float fraction = 1f / (float)_segmentCount;
        return Vector2.Lerp(posA, posB, fraction * segmentIndex);
    }
    void GenerateRope()
    {
        segments = new Transform[_segmentCount];

        for (int i = 0; i < _segmentCount; i++)
        {

            var currJoint = Instantiate(_hingeJoint, GetSegmentPosition(i), Quaternion.identity, this.transform);
            segments[i] = currJoint.transform;

            if (i > 0) // Not first hinge
            {
                int prevIndex = i - 1;
                currJoint.connectedBody = segments[prevIndex].GetComponent<Rigidbody2D>();
            }
        }
    }

}

Inspector for Rope + Segment GameObjects before running the game:

I've been working on creating stationary gun turrets that can shoot down missiles in my game. The bullets are affected by gravity while the missile moves in a linear path at a constant rate as if it had no acceleration or gravity.

My math is most likely wrong because it doesnt work even after I've tweaked and changed a few things.

Could someone please explain the derivation of the correct formula?

I have object A, I can get any information I want from object A (global position, velocity, etc)

I have object B, which is positioned and oriented in a certain way relative to object B. There is no parent/child relation between the 2 objects. I can't change the global position of object B, nor can I simply translate or rotate it. The only thing I can do is set the angular and linear velocities.

Is there a way for me to keep the relative position and orientation of object B when object A moves, while using only velocity? I've tried using what I could find online (including ChatGPT), but nothing seems to work. (i'm in 3D)

(Edit: after a comment, here is an example to clarify: object A can be a human character and object B his a Backpack. When the character moves, you want the backpack to remain on his back. Normally this is easily done with matrix transforms but in this case, we need to move the backpack only by controlling its angular and linear velocities)

Enlarge (credit: Getty Images)

Often times, when I am researching something about computers or coding that has been around a very long while, I will come across a document on a university website that tells me more about that thing than any Wikipedia page or archive ever could.

It's usually a PDF, though sometimes a plaintext file, on a .edu subdirectory that starts with a username preceded by a tilde (~) character. This is typically a document that a professor, faced with the same questions semester after semester, has put together to save the most time possible and get back to their work. I recently found such a document inside Princeton University's astrophysics department: "An Introduction to the X Window System," written by Robert Lupton.

X Window System, which turned 40 years old earlier this week, was something you had to know how to use to work with space-facing instruments back in the early 1980s, when VT100s, VAX-11/750s, and Sun Microsystems boxes would share space at college computer labs. As the member of the AstroPhysical Sciences Department at Princeton who knew the most about computers back then, it fell to Lupton to fix things and take questions.

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A few centuries ago, the swirling polychromatic chaos of Jupiter’s atmosphere spawned the immense vortex that we call the Great Red Spot. From the frantic firing of billions of neurons in your brain comes your unique and coherent experience of reading these words. As pedestrians each try to weave their path on a crowded sidewalk, they begin to follow one another, forming streams that no one...

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MIT physicists and colleagues have created a five-lane superhighway for electrons that could allow ultra-efficient electronics and more. 

The work, reported in the May 10 issue of Science, is one of several important discoveries by the same team over the past year involving a material that is a unique form of graphene.

“This discovery has direct implications for low-power electronic devices because no energy is lost during the propagation of electrons, which is not the case in regular materials where the electrons are scattered,” says Long Ju, an assistant professor in the Department of Physics and corresponding author of the Science paper.

The phenomenon is akin to cars traveling down an open turnpike as opposed to those moving through neighborhoods. The neighborhood cars can be stopped or slowed by other drivers making abrupt stops or U-turns that disrupt an otherwise smooth commute.

A new material

The material behind this work, known as rhombohedral pentalayer graphene, was discovered two years ago by physicists led by Ju. “We found a goldmine, and every scoop is revealing something new,” says Ju, who is also affiliated with MIT’s Materials Research Laboratory.

In a Nature Nanotechnology paper last October, Ju and colleagues reported the discovery of three important properties arising from rhombohedral graphene. For example, they showed that it could be topological, or allow the unimpeded movement of electrons around the edge of the material but not through the middle. That resulted in a superhighway, but required the application of a large magnetic field some tens of thousands times stronger than the Earth’s magnetic field.

In the current work, the team reports creating the superhighway without any magnetic field.

Tonghang Han, an MIT graduate student in physics, is a co-first author of the paper. “We are not the first to discover this general phenomenon, but we did so in a very different system. And compared to previous systems, ours is simpler and also supports more electron channels.” Explains Ju, “other materials can only support one lane of traffic on the edge of the material. We suddenly bumped it up to five.”

Additional co-first authors of the paper who contributed equally to the work are Zhengguang Lu and Yuxuan Yao. Lu is a postdoc in the Materials Research Laboratory. Yao conducted the work as a visiting undergraduate student from Tsinghua University. Other authors are MIT professor of physics Liang Fu; Jixiang Yang and Junseok Seo, both MIT graduate students in physics; Chiho Yoon and Fan Zhang of the University of Texas at Dallas; and Kenji Watanabe and Takashi Taniguchi of the National Institute for Materials Science in Japan.

How it works

Graphite, the primary component of pencil lead, is composed of many layers of graphene, a single layer of carbon atoms arranged in hexagons resembling a honeycomb structure. Rhombohedral graphene is composed of five layers of graphene stacked in a specific overlapping order.

Ju and colleagues isolated rhombohedral graphene thanks to a novel microscope Ju built at MIT in 2021 that can quickly and relatively inexpensively determine a variety of important characteristics of a material at the nanoscale. Pentalayer rhombohedral stacked graphene is only a few billionths of a meter thick.

In the current work, the team tinkered with the original system, adding a layer of tungsten disulfide (WS₂). “The interaction between the WS₂ and the pentalayer rhombohedral graphene resulted in this five-lane superhighway that operates at zero magnetic field,” says Ju.

Comparison to superconductivity

The phenomenon that the Ju group discovered in rhombohedral graphene that allows electrons to travel with no resistance at zero magnetic field is known as the quantum anomalous Hall effect. Most people are more familiar with superconductivity, a completely different phenomenon that does the same thing but happens in very different materials.

Ju notes that although superconductors were discovered in the 1910s, it took some 100 years of research to coax the system to work at the higher temperatures necessary for applications. “And the world record is still well below room temperature,” he notes.

Similarly, the rhombohedral graphene superhighway currently operates at about 2 kelvins, or -456 degrees Fahrenheit. “It will take a lot of effort to elevate the temperature, but as physicists, our job is to provide the insight; a different way for realizing this [phenomenon],” Ju says.

Very exciting

The discoveries involving rhombohedral graphene came as a result of painstaking research that wasn’t guaranteed to work. “We tried many recipes over many months,” says Han, “so it was very exciting when we cooled the system to a very low temperature and [a five-lane superhighway operating at zero magnetic field] just popped out.”

Says Ju, “it’s very exciting to be the first to discover a phenomenon in a new system, especially in a material that we uncovered.”

This work was supported by a Sloan Fellowship; the U.S. National Science Foundation; the U.S. Office of the Under Secretary of Defense for Research and Engineering; the Japan Society for the Promotion of Science KAKENHI; and the World Premier International Research Initiative of Japan.