Author: MIT News

School of Science welcomes new faculty in 2023

by School of Science |

Last spring, the School of Science welcomed seven new faculty members.

Erin Chen PhD ’11 studies the communication between microbes that reside on the surface of the human body and the immune system. She focuses on the largest organ: the skin. Chen will dissect the molecular signals of diverse skin microbes and their effects on host tissues, with the goal of harnessing microbe-host interactions to engineer new therapeutics for human disease.

Chen earned her bachelor’s in biology from the University of Chicago, her PhD from MIT, and her MD from Harvard Medical School, and she completed her medical residency at the University of California at San Francisco. Chen was also a Howard Hughes Medical Institute Hanna Gray Fellow at Stanford University and an attending dermatologist at UCSF and at the San Francisco VA Medical Center. Chen returns to MIT as an assistant professor in the Department of Biology, a core member of the Broad Institute of MIT and Harvard, and an attending dermatologist at Massachusetts General Hospital.

Robert Gilliard’s research is multidisciplinary and combines various aspects of organic, inorganic, main-group, and materials chemistry. The Gilliard group specializes in the chemical synthesis of new molecules that impact the development of new catalysts and reagents, including the discovery of unknown transformations of environmentally relevant small-molecules [e.g., carbon dioxide, carbon monoxide, and dihydrogen (H2)]. In addition, he investigates the design, characterization, and reactivity of boron-based luminescent and redox-active heterocycles for use in optoelectronic applications (e.g., stimuli-responsive materials, thermochromic materials, chemical sensors).

Gilliard earned his bachelor’s degree from Clemson University and his PhD from the University of Georgia. He completed joint postdoctoral studies at the Swiss Federal Institute of Technology (ETH Zürich) and Case Western Reserve University. He served on the faculty at the University of Virginia from 2017-22. Gilliard spent time in the MIT Department of Chemistry as a 2021-22 Dr. Martin Luther King Visiting Professor. He returns as the Novartis Associate Professor of Chemistry with tenure.

Sally Kornbluth is president of MIT and a professor of biology. Before she closed her lab to focus on administration, her research focused on the biological signals that tell a cell to start dividing or to self-destruct — processes that are key to understanding cancer as well as various degenerative disorders. She has published extensively on cell proliferation and programmed cell death, studying both phenomena in a variety of organisms. Her research has helped to show how cancer cells evade this programmed death, or apoptosis, and how metabolism regulates the cell death process; her work has also clarified the role of apoptosis in regulating the duration of female fertility in vertebrates.

Kornbluth holds bachelor’s degrees in political science from Williams College and in genetics from Cambridge University. She earned her PhD in molecular oncology from Rockefeller University in 1989 and completed postdoctoral training at the University of California at San Diego. In 1994, she joined the faculty of Duke University and served in the administration as vice dean for basic science at the Duke School of Medicine (2006-2014) and later as the university’s provost (2014-2022). She is a member of the National Academy of Medicine, the National Academy of Inventors, and the American Academy of Arts and Sciences.

Daniel Lew uses fungal model systems to ask how cells orient their activities in space, including oriented growth, cell wall remodeling, and organelle segregation. Different cells take on an astonishing variety of shapes, which are often critical to be able to perform specialized cell functions like absorbing nutrients or contracting muscles. Lew studies how different cell shapes arise and how cells control the spatial distribution of their internal constituents, taking advantage of the tractability of fungal model systems, and addressing these questions using approaches from cell biology, genetics, and computational biology to understand molecular mechanisms.

Lew received a bachelor’s degree in genetics from Cambridge University followed by a PhD in molecular biology from Rockefeller University. After postdoctoral training at the Scripps Research Institute, he joined the Duke University faculty in 1994. Lew joins MIT as a professor of biology with tenure.

Eluned Smith uses rare beauty decays measured with the LHCb detector at CERN to search for new fundamental particles at mass scales above the collision energy of the Large Hadron Collider (LHC). Her group leverages data to elucidate the physics of beauty quarks, whose behavior cannot be explained by the Standard Model of particle physics. In doing so, her work aims to resolve whether the anomalies are misunderstood quantum chromodynamics or the first sign of beyond-the-Standard-Model-physics at the LHC.

Smith joins MIT as an assistant professor in the Department of Physics and the Laboratory for Nuclear Science. She earned her undergraduate and doctoral degrees at Imperial College London, which she completed in 2017. She did her first postdoc at RWTH Aachen before winning an Ambizione Fellowship from the Swiss National Science Foundation at the University of Zürich.

Gaia Stucky de Quay explores topographic signals and landscape evolution, in order to both de-convolve and quantify primary driving forces such as tectonics, climate, and local geological processes. She integrates fieldwork, lab work, modeling, and remote sensing to improve our quantitative understanding of such processes at compelling geological sites such as Martian valleys and lakes, the surfaces of icy moons, and volcanic islands in the Atlantic Ocean.

Stucky de Quay joins the Department of Earth, Atmospheric and Planetary Sciences as an assistant professor. Most recently, she was a Daly Postdoctoral Fellow at Harvard University. Previously, she was a postdoc at the University of Texas at Austin and a visiting student at the University of Chicago. Stucky de Quay earned her MS from the University College of London and a PhD from Imperial College London.

Brandon “Brady” Weissbourd uses the jellyfish, Clytia hemisphaerica, to study nervous system evolution, development, regeneration, and function. With a foundation is in systems neuroscience, his lab uses genetic and optical techniques to examine how behavior arises from the activity of networks of neurons; they investigate how the Clytia nervous system is so robust; and they use Clytia’s evolutionary position to make inferences about the ultimate origins of nervous systems.

Weissbourd received a BA in human evolutionary biology from Harvard University in 2009 and a PhD from Stanford University in 2016. He then completed postdoctoral research at Caltech and The Howard Hughes Medical Institute. He joins MIT as an assistant professor in the Department of Biology and an investigator in The Picower Institute for Learning and Memory.

This fall, the School of Science welcomes nine new faculty members.

Facundo Batista studies the fundamental biology of the immune system to develop the next generation of vaccines and therapeutics. B lymphocytes are the fulcrum of immunological memory, the source of antibodies, and the focus of vaccine development. His lab has investigated how, where, and when B cell responses take shape. In recent years, the Batista group has expanded into preclinical vaccinology, targeting viruses including HIV, malaria, influenza, and SARS-CoV-2.

Batista is an MIT professor of biology with tenure as well as the associate director and scientific director of the Ragon Institute of MGH, MIT, and Harvard. He received his PhD from the International School of Advanced Studies in Trieste, Italy, and his undergraduate degree from the University of Buenos Aires, Argentina. Prior to MIT, Batista was a tenured member of the Francis Crick Institute, a professor at Imperial College London, and a professor of microbiology and immunology at Harvard Medical School.

Anna-Christina Eilers is an observational astrophysicist. Her research focuses on the formation of the first galaxies, quasars, and supermassive black holes in the early universe, during an era known as the Cosmic Dawn. In particular, Eilers is interested in the growth of the first supermassive black holes which reside in the center of luminous, distant galaxies known as quasars, to understand how black holes evolve from small stellar remnants to billion-solar-mass black holes within very short amounts of cosmic time.

Previously, Eilers received a bachelor’s degree in physics from the University of Goettingen, a master’s degree in astrophysics from the University of Heidelberg, and a PhD in astrophysics from the Max Planck Institute for Astronomy in Heidelberg. In 2019, she was awarded a NASA Hubble Fellowship and the Pappalardo Fellowship to continue her research at MIT. Eilers remains at MIT as an assistant professor in the Department of Physics and the MIT Kavli Institute for Astrophysics and Space Research.

Masha Elkin combines catalyst development, natural products synthesis, and machine learning to tackle important chemical challenges. Her group develops new transition metal catalysts that enable efficient bond disconnections and access to value-added compounds, leveraging these transformations for the synthesis of bioactive natural products that address outstanding needs in human health, and uses computational tools to explore all possible molecules and accelerate reaction discovery.

Elkin joins MIT as the D. Reid (1941) and Barbara J. Weedon Career Development Assistant Professor of Chemistry. She earned her bachelor’s degree in chemistry from Washington University in St. Louis in 2014, and her PhD from Yale University in 2019, then began as a postdoc at the University of California at Berkeley.

Mikhail Ivanov’s research has developed at the interface of theoretical physics and data analysis, bridging state-of-the-art theoretical ideas with observational data. The overarching aim of his research is to use Effective Field Theory in combination with astrophysical data in order to resolve fundamental challenges of modern physics, such as the nature of dark matter, dark energy, inflation, and gravity.

Ivanov joins MIT as an assistant professor in the Department of Physics and the Center for Theoretical Physics in the Laboratory for Nuclear Science. He obtained his PhD from the École Polytechnique Fédérale de Lausanne in 2019. During his PhD studies, he spent a year at the Institute for Advanced Study in Princeton, New Jersey, as a fellow of the Swiss National Science Foundation. Subsequently, he was a postdoc at New York University and a NASA Einstein Fellow at the Institute for Advanced Study.

Efforts to target pathogenic proteins with drugs or chemical probes can often be analogized to a lock and key, where the protein target is the “lock” and the molecule is the “key.” However, what happens when the target is flexible or lacks a defined structure? In all living things, molecular chaperone proteins have evolved to support proper folding of these moving targets. Yet, protein misfolding and aggregation is a hallmark of many myopathies and neurodegenerative diseases.

Oleta Johnson uses chemical and biophysical tools to understand and tune the activity of molecular chaperone proteins in protein misfolding diseases. Thus, her research group will reveal the molecular underpinnings of molecular chaperone dysfunction in a broad array of disorders including Huntington’s disease and Parkinson’s disease. These tools and finding will be further developed to develop novel treatments for patients of these diseases.

Johnson joins the Department of Chemistry as an assistant professor. She earned her bachelor’s degree in biochemistry from Florida Agricultural and Mechanical University in 2013, and her PhD from the University of Michigan in 2018. Prior to MIT, Johnson completed postdoctoral research at the University of California at San Francisco.

Nicole Xike Nie is an isotope geo/cosmochemist using the chemical and isotopic compositions of extraterrestrial materials to understand the formation of our solar system. Her research is driven by fundamental questions about the origin and evolution of the early solar system. Leveraging geochemical methods, she wants to understand questions such as why all planetary bodies are depleted of volatile elements when their building block materials aren’t, and why the Earth’s chemical signatures are distinct from other planetary bodies.

Nie joins MIT as an assistant professor in the Department of Earth, Atmospheric and Planetary Sciences. Nie received a BS in geology from China University of Geosciences in 2010, an MS in geochemistry from Chinese Academy of Sciences in 2013, and a PhD in geo/cosmochemistry from the University of Chicago in 2019. After graduating she was a Carnegie Postdoc Fellow at Carnegie Institution for Science and a postdoc researcher at Caltech.

Tristan Ozuch works in the field of geometric analysis and focuses on Einstein manifolds and Ricci flows. His work has shed light on the moduli space of Einstein metrics in four dimensions, addressing questions that have lingered since the 1980s. These questions originated from the systematic study of Einstein’s equations and their degenerations since the 1970s, in both physics and mathematics.

After receiving a bachelor’s degree, master’s degree, and PhD from École Normale Supérieure, Tristan Ozuch joined MIT as a C.L.E. Moore Instructor of Mathematics. He continues in the Department of Mathematics as an assistant professor.

Climate scientist Talia Tamarin-Brodsky’s research is driven by questions on the interface between weather and climate. In her work, Tamarin-Brodsky combines theory, computational methods, and observational data to study Earth’s climate and weather and how they respond to climate change. Her interests include atmospheric dynamics, temperature variability, weather and climate extremes, and subseasonal-to-seasonal predictability. For example, she studies how nonlinear wave breaking events in the upper atmosphere influence surface weather and extremes, and the mechanisms shaping the spatial distribution of Earth’s near-surface temperature.

Tamarin-Brodsky received a bachelor’s degree in mathematics and geophysics as well as a master’s in physics from Tel Aviv University, Israel, before earning her PhD from the Weizmann Institute. She completed a postdoctoral project at the University of Reading, U.K., and a postdoctoral fellowship at Tel Aviv University. She joins the Department of Earth, Atmospheric and Planetary Studies as an assistant professor.

John Urschel PhD ’21 is a mathematician focused on matrix analysis and computations, with an emphasis on theoretical results and provable guarantees for practical problems. His research interests include numerical linear algebra, spectral graph theory, and topics in theoretical machine learning.

Urschel earned bachelor’s and master’s degrees in mathematics from Pennsylvania State University, then completed a PhD in mathematics at MIT in 2021. He was a member of the Institute for Advanced Study and a junior fellow at Harvard University before returning to MIT as an assistant professor of mathematics this fall.

Future science at the molecular level

by Daniel de Wolff | MIT Industrial Liaison Program |

Innovating at the intersection of chemistry, biology, and engineering, Professor Brad Pentelute and the Pentelute Lab at MIT invent new chemistry, platforms, and techniques that might revolutionize therapeutics. Their formula in brief: nature-inspired research that begins at the molecular level, infused with state-of-the-art machine learning and automation, aimed at solving real-world problems.

Take, for example, biotechnology’s longstanding protein delivery problem. Effective intracellular protein delivery has vast potential for improving human health and curing disease. The key challenge is delivering large molecules (e.g., peptides, proteins, and oligonucleotides) into cells.

Pentelute and his team of researchers decided to see what they could learn from nature’s delivery systems for large molecules. More specifically, they investigated anthrax. The deadly toxin happens to be very good at inserting proteins into cells, explains Pentelute, whose postdoctoral work at Harvard Medical School looked at how infectious agents infiltrate cells at the molecular level.

Pentelute and his team modified the deadly toxin into a vehicle for delivering antibody and peptide variants that can be used to treat cancer. As Pentelute explains, “We essentially hijack the anthrax delivery system to get proteins into the cell. Our discovery will significantly aid in the development of durable cell-based protein therapeutics.”

Meanwhile, he has spent 12 years building an automated protein printing machine, which started in collaboration with MIT Professor Klaus Jensen. Their innovation borrows its design from nature’s ribosome, which stitches together amino acids to create proteins in just minutes. And while their human-made version is not as fast as its inspiration — not yet, anyway, according to Pentelute — it does help to accelerate the scientific experiment and drug discovery process.

“We’ve built the world’s fastest and most efficient machine of its kind; it is capable of producing thousands of amide bonds an order of magnitude faster than commercially available instruments,” says Pentelute. Meaning it might just accelerate the manufacturing of on-demand personalized therapies like cancer vaccines. To date, the platform is used by labs across MIT’s campus. It is also the basis for Amide Technologies, a startup Pentelute helped launch to scale his creation.

He and his group at MIT have built other platforms, too, including one that discovers new biologically active peptides and proteins capable of disrupting the spread of cancer. Based on affinity selection mass spectrometry, Pentelute says their invention proved particularly useful at the height of the Covid-19 pandemic. It allowed them to be among the first to discover numerous peptidomimetics that can bind to the ACE2 receptor, which is necessary for SARS-CoV-2 to enter cells. They also discovered some of the first peptides that bind to the coronavirus spike protein.

These discoveries led Pentelute and his group to the realization that they were building a rapid response platform that, as Pentelute puts it, “can look at a protein or some biology of interest and rapidly identify new ligands, new binders that could eventually be used either for assays or potential starting points for drugs.”

Based on the technology, Pentelute helped launch a pharmaceutical startup called Decoy Therapeutics. Pentelute says, “Today, Decoy is working to build a nasal formulation based on a peptide that we’ve designed that can inhibit viral progression and transmission. We’re testing that right now, and it looks quite exciting.”

As well-versed as he is in translating ideas from the lab to the real world, it is no surprise that Pentelute credits industry wants and needs as an important driver of innovation in his research program. It is also why he believes the MIT Industrial Liaison Program (MIT ILP), well established as industry’s most comprehensive portal to the Institute, is an essential aspect of the MIT innovation ecosystem. “MIT ILP has been a phenomenal partner to my lab,” he says. “We’ve put together at least 10 sponsored research agreements that started with the ILP introductions. It’s a great way to network, connect, and try new approaches to problem-solving.”

Ask Pentelute about the future of his research, and he will tell you he and his group are hard at work generating molecular data to establish systems capable of training algorithms to design molecules with new functions. In reference to the work, he says, “We were the first people in the world to use machine learning to design miniature abiotic (not designed by nature) cell-penetrating proteins.”

One of their collaborators on the new project is Professor Manolis Kellis of the MIT Computer Science and Artificial Intelligence Laboratory. Kellis is well known for his groundbreaking work exploring genome-level changes as causal drivers of disease. “We’re building knowledge trees to understand what is driving, for instance, obesity,” Pentelute explains, “and then we’re going to come over to my laboratory and figure out how to rapidly make and test these molecules.”

Joining the MIT professors in their endeavor is Harvard Medical School’s Marinka Zitnik. She is at the forefront of building the Therapeutic Data Commons, which gathers data to build machine learning models to accelerate drug development. “With Marinka’s help, before we do experiments, we can ask questions about how a molecule, given its particular design, might work within a human,” says Pentelute.

“This is a critical moment in terms of the way we do science,” says Pentelute. “We’re converging to build a new paradigm of thinking through the AI-driven design of molecules to interact with humans. In the future, we’ll be able to design molecules as needed to impact not just human health, but everything that we experience here on earth. We’re leapfrogging into a new space of innovation — that’s what drives me, and that’s what we’re trying to build here at the Pentelute Lab.”

Arrays of quantum rods could enhance TVs or virtual reality devices

by Anne Trafton | MIT News Office |

Flat screen TVs that incorporate quantum dots are now commercially available, but it has been more difficult to create arrays of their elongated cousins, quantum rods, for commercial devices. Quantum rods can control both the polarization and color of light, to generate 3D images for virtual reality devices.

Using scaffolds made of folded DNA, MIT engineers have come up with a new way to precisely assemble arrays of quantum rods. By depositing quantum rods onto a DNA scaffold in a highly controlled way, the researchers can regulate their orientation, which is a key factor in determining the polarization of light emitted by the array. This makes it easier to add depth and dimensionality to a virtual scene.

“One of the challenges with quantum rods is: How do you align them all at the nanoscale so they’re all pointing in the same direction?” says Mark Bathe, an MIT professor of biological engineering and the senior author of the new study. “When they’re all pointing in the same direction on a 2D surface, then they all have the same properties of how they interact with light and control its polarization.”

MIT postdocs Chi Chen and Xin Luo are the lead authors of the paper, which appears today in Science Advances. Robert Macfarlane, an associate professor of materials science and engineering; Alexander Kaplan PhD ’23; and Moungi Bawendi, the Lester Wolfe Professor of Chemistry, are also authors of the study.

Nanoscale structures

Over the past 15 years, Bathe and others have led in the design and fabrication of nanoscale structures made of DNA, also known as DNA origami. DNA, a highly stable and programmable molecule, is an ideal building material for tiny structures that could be used for a variety of applications, including delivering drugs, acting as biosensors, or forming scaffolds for light-harvesting materials.

Bathe’s lab has developed computational methods that allow researchers to simply enter a target nanoscale shape they want to create, and the program will calculate the sequences of DNA that will self-assemble into the right shape. They also developed scalable fabrication methods that incorporate quantum dots into these DNA-based materials.

In a 2022 paper, Bathe and Chen showed that they could use DNA to scaffold quantum dots in precise positions using scalable biological fabrication. Building on that work, they teamed up with Macfarlane’s lab to tackle the challenge of arranging quantum rods into 2D arrays, which is more difficult because the rods need to be aligned in the same direction.

Existing approaches that create aligned arrays of quantum rods using mechanical rubbing with a fabric or an electric field to sweep the rods into one direction have had only limited success. This is because high-efficiency light-emission requires the rods to be kept at least 10 nanometers from each other, so that they won’t “quench,” or suppress, their neighbors’ light-emitting activity.

To achieve that, the researchers devised a way to attach quantum rods to diamond-shaped DNA origami structures, which can be built at the right size to maintain that distance. These DNA structures are then attached to a surface, where they fit together like puzzle pieces.

“The quantum rods sit on the origami in the same direction, so now you have patterned all these quantum rods through self-assembly on 2D surfaces, and you can do that over the micron scale needed for different applications like microLEDs,” Bathe says. “You can orient them in specific directions that are controllable and keep them well-separated because the origamis are packed and naturally fit together, as puzzle pieces would.”

Assembling the puzzle

As the first step in getting this approach to work, the researchers had to come up with a way to attach DNA strands to the quantum rods. To do that, Chen developed a process that involves emulsifying DNA into a mixture with the quantum rods, then rapidly dehydrating the mixture, which allows the DNA molecules to form a dense layer on the surface of the rods.

This process takes only a few minutes, much faster than any existing method for attaching DNA to nanoscale particles, which may be key to enabling commercial applications.

“The unique aspect of this method lies in its near-universal applicability to any water-loving ligand with affinity to the nanoparticle surface, allowing them to be instantly pushed onto the surface of the nanoscale particles. By harnessing this method, we achieved a significant reduction in manufacturing time from several days to just a few minutes,” Chen says.

These DNA strands then act like Velcro, helping the quantum rods stick to a DNA origami template, which forms a thin film that coats a silicate surface. This thin film of DNA is first formed via self-assembly by joining neighboring DNA templates together via overhanging strands of DNA along their edges.

The researchers now hope to create wafer-scale surfaces with etched patterns, which could allow them to scale their design to device-scale arrangements of quantum rods for numerous applications, beyond only microLEDs or augmented reality/virtual reality.

“The method that we describe in this paper is great because it provides good spatial and orientational control of how the quantum rods are positioned. The next steps are going to be making arrays that are more hierarchical, with programmed structure at many different length scales. The ability to control the sizes, shapes, and placement of these quantum rod arrays is a gateway to all sorts of different electronics applications,” Macfarlane says.

“DNA is particularly attractive as a manufacturing material because it can be biologically produced, which is both scalable and sustainable, in line with the emerging U.S. bioeconomy. Translating this work toward commercial devices by solving several remaining bottlenecks, including switching to environmentally safe quantum rods, is what we’re focused on next,” Bathe adds.

The research was funded by the Office of Naval Research, the National Science Foundation, the Army Research Office, the Department of Energy, and the National Institute of Environmental Health Sciences.

Fourteen MIT School of Science professors receive tenure for 2022 and 2023

by School of Science |

In 2022, nine MIT faculty were granted tenure in the School of Science:

Gloria Choi examines the interaction of the immune system with the brain and the effects of that interaction on neurodevelopment, behavior, and mood. She also studies how social behaviors are regulated according to sensory stimuli, context, internal state, and physiological status, and how these factors modulate neural circuit function via a combinatorial code of classic neuromodulators and immune-derived cytokines. Choi joined the Department of Brain and Cognitive Sciences after a postdoc at Columbia University. She received her bachelor’s degree from the University of California at Berkeley, and her PhD from Caltech. Choi is also an investigator in The Picower Institute for Learning and Memory.

Nikta Fakhri develops experimental tools and conceptual frameworks to uncover laws governing fluctuations, order, and self-organization in active systems. Such frameworks provide powerful insight into dynamics of nonequilibrium living systems across scales, from the emergence of thermodynamic arrow of time to spatiotemporal organization of signaling protein patterns and discovery of odd elasticity. Fakhri joined the Department of Physics in 2015 following a postdoc at University of Göttingen. She completed her undergraduate degree at Sharif University of Technology and her PhD at Rice University.

Geobiologist Greg Fournier uses a combination of molecular phylogeny insights and geologic records to study major events in planetary history, with the hope of furthering our understanding of the co-evolution of life and environment. Recently, his team developed a new technique to analyze multiple gene evolutionary histories and estimated that photosynthesis evolved between 3.4 and 2.9 billion years ago. Fournier joined the Department of Earth, Atmospheric and Planetary Sciences in 2014 after working as a postdoc at the University of Connecticut and as a NASA Postdoctoral Program Fellow in MIT’s Department of Civil and Environmental Engineering. He earned his BA from Dartmouth College in 2001 and his PhD in genetics and genomics from the University of Connecticut in 2009.

Daniel Harlow researches black holes and cosmology, viewed through the lens of quantum gravity and quantum field theory. His work generates new insights into quantum information, quantum field theory, and gravity. Harlow joined the Department of Physics in 2017 following postdocs at Princeton University and Harvard University. He obtained a BA in physics and mathematics from Columbia University in 2006 and a PhD in physics from Stanford University in 2012. He is also a researcher in the Center for Theoretical Physics.

A biophysicist, Gene-Wei Li studies how bacteria optimize the levels of proteins they produce at both mechanistic and systems levels. His lab focuses on design principles of transcription, translation, and RNA maturation. Li joined the Department of Biology in 2015 after completing a postdoc at the University of California at San Francisco. He earned an BS in physics from National Tsinghua University in 2004 and a PhD in physics from Harvard University in 2010.

Michael McDonald focuses on the evolution of galaxies and clusters of galaxies, and the role that environment plays in dictating this evolution. This research involves the discovery and study of the most distant assemblies of galaxies alongside analyses of the complex interplay between gas, galaxies, and black holes in the closest, most massive systems. McDonald joined the Department of Physics and the Kavli Institute for Astrophysics and Space Research in 2015 after three years as a Hubble Fellow, also at MIT. He obtained his BS and MS degrees in physics at Queen’s University, and his PhD in astronomy at the University of Maryland in College Park.

Gabriela Schlau-Cohen combines tools from chemistry, optics, biology, and microscopy to develop new approaches to probe dynamics. Her group focuses on dynamics in membrane proteins, particularly photosynthetic light-harvesting systems that are of interest for sustainable energy applications. Following a postdoc at Stanford University, Schlau-Cohen joined the Department of Chemistry faculty in 2015. She earned a bachelor’s degree in chemical physics from Brown University in 2003 followed by a PhD in chemistry at the University of California at Berkeley.

Phiala Shanahan’s research interests are focused around theoretical nuclear and particle physics. In particular, she works to understand the structure and interactions of hadrons and nuclei from the fundamental degrees of freedom encoded in the Standard Model of particle physics. After a postdoc at MIT and a joint position as an assistant professor at the College of William and Mary and senior staff scientist at the Thomas Jefferson National Accelerator Facility, Shanahan returned to the Department of Physics as faculty in 2018. She obtained her BS from the University of Adelaide in 2012 and her PhD, also from the University of Adelaide, in 2015.

Omer Yilmaz explores the impact of dietary interventions on stem cells, the immune system, and cancer within the intestine. By better understanding how intestinal stem cells adapt to diverse diets, his group hopes to identify and develop new strategies that prevent and reduce the growth of cancers involving the intestinal tract. Yilmaz joined the Department of Biology in 2014 and is now also a member of Koch Institute for Integrative Cancer Research. After receiving his BS from the University of Michigan in 1999 and his PhD and MD from University of Michigan Medical School in 2008, he was a resident in anatomic pathology at Massachusetts General Hospital and Harvard Medical School until 2013.

In 2023, five MIT faculty were granted tenure in the School of Science:

Physicist Riccardo Comin explores the novel phases of matter that can be found in electronic solids with strong interactions, also known as quantum materials. His group employs a combination of synthesis, scattering, and spectroscopy to obtain a comprehensive picture of these emergent phenomena, including superconductivity, (anti)ferromagnetism, spin-density-waves, charge order, ferroelectricity, and orbital order. Comin joined the Department of Physics in 2016 after postdoctoral work at the University of Toronto. He completed his undergraduate studies at the Universita’ degli Studi di Trieste in Italy, where he also obtained a MS in physics in 2009. Later, he pursued doctoral studies at the University of British Columbia, Canada, earning a PhD in 2013.

Netta Engelhardt researches the dynamics of black holes in quantum gravity and uses holography to study the interplay between gravity and quantum information. Her primary focus is on the black hole information paradox, that black holes seem to be destroying information that, according to quantum physics, cannot be destroyed. Engelhardt was a postdoc at Princeton University and a member of the Princeton Gravity Initiative prior to joining the Department of Physics in 2019. She received her BS in physics and mathematics from Brandeis University and her PhD in physics from the University of California at Santa Barbara. Engelhardt is a researcher in the Center for Theoretical Physics and the Black Hole Initiative at Harvard University.

Mark Harnett studies how the biophysical features of individual neurons endow neural circuits with the ability to process information and perform the complex computations that underlie behavior. As part of this work, his lab was the first to describe the physiological properties of human dendrites. He joined the Department of Brain and Cognitive Sciences and the McGovern Institute for Brain Research in 2015. Prior, he was a postdoc at the Howard Hughes Medical Institute’s Janelia Research Campus. He received his BA in biology from Reed College in Portland, Oregon and his PhD in neuroscience from the University of Texas at Austin.

Or Hen investigates quantum chromodynamic effects in the nuclear medium and the interplay between partonic and nucleonic degrees of freedom in nuclei. Specifically, Hen utilizes high-energy scattering of electron, neutrino, photon, proton and ion off atomic nuclei to study short-range correlations: temporal fluctuations of high-density, high-momentum, nucleon clusters in nuclei with important implications for nuclear, particle, atomic, and astrophysics. Hen was an MIT Pappalardo Fellow in the Department of Physics from 2015 to 2017 before joining the faculty in 2017. He received his undergraduate degree in physics and computer engineering from the Hebrew University and earned his PhD in experimental physics at Tel Aviv University.

Sebastian Lourido is interested in learning about the vulnerabilities of parasites in order to develop treatments for infectious diseases and expand our understanding of eukaryotic diversity. His lab studies many important human pathogens, including Toxoplasma gondii, to model features conserved throughout the phylum. Lourido was a Whitehead Fellow at the Whitehead Institute for Biomedical Research until 2017, when he joined the Department of Biology and became a Whitehead Member. He earned his BS from Tulane University in 2004 and his PhD from Washington University in St. Louis in 2012.

Helping to fill in gaps in urology research for female patients

by Lillian Eden | Department of Biology |

There were early signs that Nicole De Nisco ’07, PhD ’13 might become a scientist. She ran out of science classes to take in high school and fondly remembers the teacher that encouraged her to pursue science instead of the humanities. But she ended up at MIT, in part, out of spite.

“I applied because my guidance counselor told me I wouldn’t get in,” she says. The rest, as they say, is history for the first-generation college student from Los Angeles.

Now, she’s an assistant professor of biological sciences at the University of Texas at Dallas studying urinary tract infections (UTIs) and the urinary microbiome in postmenopausal women.

De Nisco has already made some important advancements in the field: She developed a new technique for visualizing bacteria in the bladder and used it to demonstrate that bacteria form reservoirs in human bladder tissue, leading to chronic or recurrent UTIs.

It was known that in mice, bacteria are able to create communities within the bladder tissue, forming reservoirs and staying there long term — but no one had shown that occurring in human tissue before.

De Nisco found that reservoirs of tissue-resident bacteria exist in human patients with recurring UTIs, a condition which may ultimately lead to women needing to have their bladder removed. De Nisco now mostly works with postmenopausal women who have been suffering from decades of recurring UTIs.

There was a big gap in the field, De Nisco explains, so entering the field of urology was also an opportunity to make new discoveries and find new ways to treat those recurring infections.

De Nisco says she’s in the minority, both as a woman studying urology and as someone studying diseases that affect female patients. Most researchers in the urology field are men, and most focus on the prostate.

But things are changing.

“I think there are a lot of women in the field who are now pushing back, and I actually collaborate with a lot of other female investigators in the field. We’re trying to support each other so that we can survive and, hopefully, actually advance the science — instead of it being in the same place it was 15 years ago,” De Nisco says.

De Nisco first fell in love with biomedical research as an undergrad doing an Undergraduate Research Opportunities Program project in Catherine Drennan’s lab, back when Drennan was still located in the chemistry building.

“Cathy herself was incredibly encouraging, and is probably the main reason I decided to pursue a career in science — or felt that I could,” De Nisco says.

De Nisco became fascinated with the dialogue between a microbe and a host organism during an undergraduate course in microbial physiology with Graham Walker, which led to De Nisco’s decision to remain at MIT for her PhD work and to perform her doctoral research in rhizobia legume symbiosis in Walker’s lab.

De Nisco says that during her time at MIT, Drennan and Walker gave her a lot of encouragement and “room to do my own thing,” fostering a love of discovery and problem-solving. It’s a mentoring style she’s using now with her own graduate students; she currently has eight working in her lab.

“Every student is different: some just want a project and they want to know what they’re doing, and some want to explore,” she says. “I was the type that wanted to do my own thing, and so they gave me the room and the patience to be able to explore and find something new that I was interested in and excited about.”

As a low-income student sending financial help home, she also pursued teaching opportunities outside of her usual duties; Walker was very supportive of pursuing other teaching opportunities. De Nisco was a graduate student tutor for Next House watching over 40 undergrads, served as a teaching fellow with the Harvard Extension School, and worked with Eric Lander to help launch the course 7.00x (Introduction to Biology – The Secret of Life for EdX), one of the most highly rated online courses of all time.

She said MIT definitely prepared her for a life as a professor, teacher, and mentor; the most important thing about graduate school isn’t choosing “the most cutting-edge research project,” but making sure you have a good training experience and an advisor who can provide that.

“You don’t need to start building your name in the field when you’re a grad student. The lab environment is much more important than the topic. It’s easy to get burned out or to be turned off to a career in academia altogether if you have the wrong advisor,” she says. “You need to learn how to be a scientist, and you have plenty of time later in your career to follow whatever path you want to follow.”

She knows this from experience: Her current research is somewhat parallel but unrelated to her previous research experience.

“I think my motivation for being a scientist is rooted in my desire to help people doing something I enjoy,” she says. “I was not doing this kind of research as a graduate student, and that doesn’t mean that I wasn’t able to end up at this point in my career where I’m doing research that is focused on improving the lives of women, specifically.”

She did her postdoctoral work at UT Southwestern Medical Center studying Vibrio parahaemolyticus, a human pathogen that causes gastroenteritis. The work was a marriage of her interests in biochemistry and host-microbiome interactions.

She says MIT prepared her well for the type of interdisciplinary work that she does every day: At UT Dallas, all the research buildings are fully integrated, with engineers, chemists, physicists, and biologists sharing lab spaces in the same building. Her closest collaborators are mathematicians, chemists, and engineers.

Although she may not be fully literate in all of those disciplines, she shares a common language with the people she works with thanks to MIT’s undergraduate course requirements in many different topics and MIT’s focus on interdisciplinary research, which is “how real advancement is made.”

Ultimately, De Nisco says she is glad to this day that she attended MIT.

“Getting that acceptance letter to attend MIT probably changed the trajectory of my life,” she says. “You never know, on paper, what someone is going to achieve eventually, and what kind of force they’re going to be. I’m always grateful to whoever was on the admissions committees that made the decision to accept me — twice.”

Probe expands understanding of oral cavity homeostasis

by Lillian Eden | Department of Biology |

Your mouth is a crucial interface between the outside world and the inside of your body. Everything you breathe, chew, or drink interacts with your oral cavity — the proteins and the microbes, including microbes that can harm us. When things go awry, the result can range from the mild, like bad breath, to the serious, like tooth and gum decay, to more dire effects in the gut and other parts of the body.

Even though the oral microbiome plays a critical role as a front-line defense for human health and disease, we still know very little about the intricacies of host-microbe interactions in the complex physiological environment of the mouth; a better understanding of those interactions is key to developing treatments for human disease.

In a recent study published in PNAS, a team of scientists from MIT and elsewhere revealed that one of the most abundant proteins found in our saliva binds to the surface of select microbes found in the mouth. The findings shed light on how salivary proteins and mucus play a role in maintaining the oral cavity microbiome.

The collaboration involved members of the labs of Barbara Imperiali in the MIT Department of Biology and Laura Kiessling in the MIT Department of Chemistry, as well as the groups of Stefan Ruhl at the University at Buffalo School of Dental Medicine and Catherine Grimes at the University of Delaware.

The work is focused on an abundant oral cavity protein called zymogen granule protein 16 homolog B (ZG16B). Finding ZG16B’s interaction partners and gaining insight into its function were the overarching goals of the project. To accomplish this, Soumi Ghosh, a postdoc in the Imperiali lab, and colleagues engineered ZG16B to add reporter tags such as fluorophores. They called these modified proteins “microbial glycan analysis probes (mGAPs)” because they allowed them to identify ZG16B binding partners using complementary methods. They applied the probes to samples of healthy oral microbiomes to identify target microbes and binding partners.

The results excited them.

“ZG16B didn’t just bind to random bacteria. It was very focused on certain species, including a commensal bacteria called Streptococcus vestibularis,” says Ghosh, who is first author on the paper.

Commensal bacteria are found in a normal healthy microbiome and do not cause disease.

Using the mGAPs, the team showed that ZG16B binds to cell wall polysaccharides of the bacteria, which indicates that ZG16B is a lectin, a carbohydrate-binding protein. In general, lectins are responsible for cell-cell interactions, signaling pathways, and some innate immune responses against pathogens. “This is the first time that it has been proven experimentally that ZG16B acts as a lectin because it binds to the carbohydrates on the cell surface or cell wall of the bacteria,” Ghosh highlights.

ZG16B was also shown to recruit Mucin 7 (MUC7), a salivary glycoprotein in the oral cavity, and together the results suggest that ZG16B may help maintain a healthy balance in the oral microbiome by forming a complex with MUC7 and certain bacteria. The results indicate that ZG16B regulates the bacteria’s abundance by preventing overgrowth through agglutination when the bacteria exceed a certain level of growth.

“ZG16B, therefore, seems to function as a missing link in the system; it binds to different types of glycans — the microbial glycans and the mucin glycans — and ultimately, maintains a healthy balance in our oral cavity,” Ghosh says.

Further work with this probe and samples of oral microbiome from healthy and diseased subjects could also reveal the lectin’s importance for oral health and disease.

Current attention is focused on developing and applying additional mGAPs based on other human lectins, such as those found in serum, liver, and intestine to reveal their binding specificities and their roles in host-microbe interactions.

“The research carried out in this collaboration exemplifies the kind of synergy that made me excited to move to MIT five years ago,” says Kiessling. “I’ve been able to work with outstanding scientists who share my interest in the chemistry and the biology of carbohydrates.”

Kiessling and Imperiali, both senior authors of the paper, came up with the term for the probes they’re creating: “mGAPS to fill in the gaps” in our understanding of the role of lectins in the human microbiome, according to Ghosh.

“If we want to develop therapeutics against bacterial infection, we need a better understanding of host-microbe interactions,” Ghosh says. “The significance of our study is to prove that we can make very good probes for microbial glycans, find out their importance in the front-line defense of the immune system, and, ultimately, come up with a therapeutic approach to disease.”

This research was supported by the National Institute of Health.

How Tau tangles form in the brain

by Anne Trafton | MIT News Office |

Many neurodegenerative diseases, including Alzheimer’s, are characterized by tangled proteins called Tau fibrils. In a new study, MIT chemists have gained insight into how these fibrils form, and identified a potential target for drugs that could interfere with this formation.

In the new study, the researchers discovered that one segment of the Tau protein is more flexible than expected, and this flexibility helps the fibrils take on a variety of different shapes. They also showed that these fibrils are more likely to form when the ends of the Tau protein are lopped off.

“This protein cleavage happens relatively early in Alzheimer’s disease, and that helps to speed up aggregation, which is undesirable,” says Mei Hong, an MIT professor of chemistry and the senior author of the new study.

The researchers also pinpointed a sequence of amino acids that appears to help the Tau protein bend in different directions, which they believe could make a good target for drugs that would interfere with the formation of Tau tangles.

MIT postdoc Nadia El Mammeri is the lead author of the study, which appears today in Science Advances. MIT postdocs Pu Duan and Aurelio Dregni are also authors of the paper.

Fibril formation

In the healthy brain, Tau proteins bind to microtubules and help to stabilize them. The protein contains four repeating subunits, each slightly different, known as R1, R2, R3, and R4. In the brains of people with Alzheimer’s and other neurodegenerative diseases, abnormal versions of Tau form stringy filaments that clump together, causing tangles in the brain.

Learning more about the structures of those filaments could help researchers figure out how abnormal Tau proteins become misfolded, but studying those filaments has been difficult because of their inherently disordered structure. In this study, the researchers used nuclear magnetic resonance (NMR) to determine some of those structures, using a version of the Tau protein generated in the lab using recombinant DNA.

The researchers focused on the central core of the Tau protein, where folded protein strands called beta sheets create a very rigid structure. This core is bookended by floppy segments. While the exact structure of these floppy segments is unknown, researchers have used electron microscopy to show that they form a “fuzzy coat” that surrounds the central core.

To explore what happens when those end segments are lost, as often happens in Alzheimer’s disease, the researchers chopped them off and then used NMR to analyze the resulting protein structure. Without those floppy segments, the researchers found that the rigid cores formed filaments much more easily. This suggests that the fuzzy coat helps to prevent the protein from forming filaments, which could have a protective effect against neurodegenerative disease.

“What that tells you is that fuzzy coat in the natural protein actually has a protective role. It slows down fibril formation. Once you strip away these sections, then the aggregation process happens much faster,” Hong says.

Protein flexibility

The researchers also found that the R3 repeat, which makes up much of the rigid core, is itself very rigid. However, the R2 repeat, which makes up the rest of the core, is more flexible and can produce different conformations, depending on environmental conditions such as temperature.

“This finding highlights how the environment influences the form and shape of the aggregate at the atomic level, similar to how a chameleon adapts its color to the environment. Small changes in temperature are sufficient to change the overall shape of the aggregate, which must be regarded as amazing and usually not observed in functional systems,” says Roland Riek, a professor of chemistry and applied biosciences at ETH Zurich, who was not involved in the study.

Under different conditions, R2 can exist as either a straight or hinged segment, the researchers showed. They believe this conformational flexibility may account for the slight differences in structure that have been seen in Tau proteins found in different diseases, including Alzheimer’s, corticobasal degeneration, and argyrophilic grain disease.

Within the R2 repeat, the researchers also identified a sequence of six amino acids that appear to make the structure more flexible than other R segments. This region could offer an accessible target for drugs that would inhibit the formation of Tau fibrils, Hong says.

“This region of R2 is conformationally plastic, so maybe this is a vulnerable spot that could be targeted by small molecule drugs,” she says. “The R3 region is so stable and rigid that it’s probably very hard to disaggregate Tau fibrils by focusing on that part.”

The researchers now plan to explore whether they can generate Tau structures that more closely match the structures of Tau proteins taken from the brains of patients with Alzheimer’s and other neurodegenerative diseases, by truncating the protein in specific locations or adding chemical modifications that have been linked with those diseases.

The research was funded by the National Institutes of Health and an NIH Ruth L. Kirschstein Individual National Research Service Award.

Chemists discover why photosynthetic light-harvesting is so efficient

by Anne Trafton | MIT News Office |

When photosynthetic cells absorb light from the sun, packets of energy called photons leap between a series of light-harvesting proteins until they reach the photosynthetic reaction center. There, cells convert the energy into electrons, which eventually power the production of sugar molecules.

This transfer of energy through the light-harvesting complex occurs with extremely high efficiency: Nearly every photon of light absorbed generates an electron, a phenomenon known as near-unity quantum efficiency.

A new study from MIT chemists offers a potential explanation for how proteins of the light-harvesting complex, also called the antenna, achieve that high efficiency. For the first time, the researchers were able to measure the energy transfer between light-harvesting proteins, allowing them to discover that the disorganized arrangement of these proteins boosts the efficiency of the energy transduction.

“In order for that antenna to work, you need long-distance energy transduction. Our key finding is that the disordered organization of the light-harvesting proteins enhances the efficiency of that long-distance energy transduction,” says Gabriela Schlau-Cohen, an associate professor of chemistry at MIT and the senior author of the new study.

MIT postdocs Dihao Wang and Dvir Harris and former MIT graduate student Olivia Fiebig PhD ’22 are the lead authors of the paper, which appears this week in the Proceedings of the National Academy of Sciences. Jianshu Cao, an MIT professor of chemistry, is also an author of the paper.

Energy capture

For this study, the MIT team focused on purple bacteria, which are often found in oxygen-poor aquatic environments and are commonly used as a model for studies of photosynthetic light-harvesting.

Within these cells, captured photons travel through light-harvesting complexes consisting of proteins and light-absorbing pigments such as chlorophyll. Using ultrafast spectroscopy, a technique that uses extremely short laser pulses to study events that happen on timescales of femtoseconds to nanoseconds, scientists have been able to study how energy moves within a single one of these proteins. However, studying how energy travels between these proteins has proven much more challenging because it requires positioning multiple proteins in a controlled way.

To create an experimental setup where they could measure how energy travels between two proteins, the MIT team designed synthetic nanoscale membranes with a composition similar to those of naturally occurring cell membranes. By controlling the size of these membranes, known as nanodiscs, they were able to control the distance between two proteins embedded within the discs.

For this study, the researchers embedded two versions of the primary light-harvesting protein found in purple bacteria, known as LH2 and LH3, into their nanodiscs. LH2 is the protein that is present during normal light conditions, and LH3 is a variant that is usually expressed only during low light conditions.

Using the cryo-electron microscope at the MIT.nano facility, the researchers could image their membrane-embedded proteins and show that they were positioned at distances similar to those seen in the native membrane. They were also able to measure the distances between the light-harvesting proteins, which were on the scale of 2.5 to 3 nanometers.

Disordered is better

Because LH2 and LH3 absorb slightly different wavelengths of light, it is possible to use ultrafast spectroscopy to observe the energy transfer between them. For proteins spaced closely together, the researchers found that it takes about 6 picoseconds for a photon of energy to travel between them. For proteins farther apart, the transfer takes up to 15 picoseconds.

Faster travel translates to more efficient energy transfer, because the longer the journey takes, the more energy is lost during the transfer.

“When a photon gets absorbed, you only have so long before that energy gets lost through unwanted processes such as nonradiative decay, so the faster it can get converted, the more efficient it will be,” Schlau-Cohen says.

The researchers also found that proteins arranged in a lattice structure showed less efficient energy transfer than proteins that were arranged in randomly organized structures, as they usually are in living cells.

“Ordered organization is actually less efficient than the disordered organization of biology, which we think is really interesting because biology tends to be disordered. This finding tells us that that may not just be an inevitable downside of biology, but organisms may have evolved to take advantage of it,” Schlau-Cohen says.

Now that they have established the ability to measure inter-protein energy transfer, the researchers plan to explore energy transfer between other proteins, such as the transfer between proteins of the antenna to proteins of the reaction center. They also plan to study energy transfer between antenna proteins found in organisms other than purple bacteria, such as green plants.

The research was funded primarily by the U.S. Department of Energy.

QS ranks MIT the world’s No. 1 university for 2023-24

by MIT News Office |

MIT has again been named the world’s top university by the QS World University Rankings, which were announced today. This is the 12th year in a row MIT has received this distinction.

The full 2024 edition of the rankings — published by Quacquarelli Symonds, an organization specializing in education and study abroad — can be found at TopUniversities.com. The QS rankings are based on factors including academic reputation, employer reputation, citations per faculty, student-to-faculty ratio, proportion of international faculty, and proportion of international students.

MIT was also ranked the world’s top university in 11 of the subject areas ranked by QS, as announced in March of this year.

The Institute received a No. 1 ranking in the following QS subject areas: Chemical Engineering; Civil and Structural Engineering; Computer Science and Information Systems; Data Science and Artificial Intelligence; Electrical and Electronic Engineering; Linguistics; Materials Science; Mechanical, Aeronautical, and Manufacturing Engineering; Mathematics; Physics and Astronomy; and Statistics and Operational Research.

MIT also placed second in five subject areas: Accounting and Finance; Architecture/Built Environment; Biological Sciences; Chemistry; and Economics and Econometrics.

Researchers develop a new source of quantum light

by David L. Chandler | MIT News Office |

Using novel materials that have been widely studied as potential new solar photovoltaics, researchers at MIT have shown that nanoparticles of these materials can emit a stream of single, identical photons.

While the work is currently a fundamental discovery of these materials’ capabilities, it might ultimately pave the way to new optically based quantum computers, as well as possible quantum teleportation devices for communication, the researchers say. The results appear today in the journal Nature Photonics, in a paper by graduate student Alexander Kaplan, professor of chemistry Moungi Bawendi, and six others at MIT.

Most concepts for quantum computing use ultracold atoms or the spins of individual electrons to act as the quantum bits, or qubits, that form the basis of such devices. But about two decades ago some researchers proposed the idea of using light instead of physical objects as the basic qubit units. Among other advantages, this would eliminate the need for complex and expensive equipment to control the qubits and enter and extract data from them. Instead, ordinary mirrors and optical detectors would be all that was needed.

“With these qubit-like photons,” Kaplan explains, “with just ‘household’ linear optics, you can build a quantum computer, provided you have appropriately prepared photons.”

The preparation of those photons is the key thing. Each photon has to precisely match the quantum characteristics of the one before, and so on. Once that perfect matching is achieved, “the really big paradigm shift then is changing from the need for very fancy optics, very fancy equipment, to needing just simple equipment. The thing that needs to be special is the light itself.”

Then, Bawendi explains, they take these single photons that are identical and indistinguishable from each other, and they interact them with each other. That indistinguishability is crucial: If you have two photons, and “everything is the same about them, and you can’t say number one and number two, you can’t keep track of them that way. That’s what allows them to interact in certain ways that are nonclassical.”

Kaplan says that “if we want the photon to have this very specific property, of being very well-defined in energy, polarization, spatial mode, time, all of the things that we can encode quantum mechanically, we need the source to be very well-defined quantum mechanically as well.”

The source they ended up using is a form of lead-halite perovskite nanoparticles. Thin films of lead-halide perovskites are being widely pursued as potential next-generation photovoltaics, among other things, because they could be much more lightweight and easier to process than today’s standard silicon-based photovoltaics. In nanoparticle form, lead-halide perovskites are notable for their blindingly fast cryogenic radiative rate, which sets them apart from other colloidal semiconductor nanoparticles. The faster the light is emitted, the more likely the output will have a well-defined wavefunction. The fast radiative rates thus uniquely position lead-halide perovskite nanoparticles to emit quantum light.

To test that the photons they generate really do have this indistinguishable property, a standard test is to detect a specific kind of interference between two photons, known as Hong-Ou-Mandel interference. This phenomenon is central to a lot of quantum-based technologies, Kaplan says, and therefore demonstrating its presence “has been a hallmark for confirming that a photon source can be used for these purposes.”

Very few materials can emit light that meets this test, he says. “They pretty much can be listed on one hand.” While their new source is not yet perfect, producing the HOM interference only about half the time, the other sources have significant issues with achieving scalability. “The reason other sources are coherent is they’re made with the purest materials, and they’re made individually one by one, atom by atom. So, there’s very poor scalability and very poor reproducibility,” Kaplan says.

By contrast, the perovskite nanoparticles are made in a solution and simply deposited on a substrate material. “We’re basically just spinning them onto a surface, in this case just a regular glass surface,” Kaplan says. “And we’re seeing them undergo this behavior that previously was seen only under the most stringent of preparation conditions.”

So, even though these materials may not yet be perfect, “They’re very scalable, we can make a lot of them. and they’re currently very unoptimized. We can integrate them into devices, and we can further improve them,” Kaplan says.

At this stage, he says, this work is “a very interesting fundamental discovery,” showing the capabilities of these materials. “The importance of the work is that hopefully it can encourage people to look into how to further enhance these in various device architectures.”

And, Bawendi adds, by integrating these emitters into reflective systems called optical cavities, as has already been done with the other sources, “we have full confidence that integrating them into an optical cavity will bring their properties up to the level of the competition.”

The research team included Chantalle Krajewska, Andrew Proppe, Weiwei Sun, Tara Sverko, David Berkinsky, and Hendrik Utzat. The work was supported by the U.S. Department of Energy and the Natural Sciences and Engineering Research Council of Canada.