News: Research

Quantum Flute

A general theory of non-reciprocal matter.

The Vitelli and Littlewood groups recently published a groundbreaking general theory of non-reciprocal matter using exceptional points and illustrated with examples found in simple systems such as groups of interacting toy robots. The work was original published in Nature in April and is now receiving wider attention via WIRED. Please see the links on the right and the UChicago News story as well.

Wired Story
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Continuing to transform electron beam technology
A collaboration of researchers led by Cornell University and including the University of Chicago has been awarded $22.5 million from the National Science Foundation to continue gaining the fundamental understanding needed to transform the brightness of electron beams available to science, medicine and industry.

­The Center for Bright Beams (CBB), an NSF Science and Technology Center, was created in 2016 with an initial $23 million award to Cornell and partner institutions, including the University of Chicago and affiliated Fermi National Accelerator Laboratory. The center integrates accelerator science with condensed matter physics, materials science and surface science in order to advance particle accelerator technologies, which play a key role in creating new breakthroughs in everything from medicine to electronics to particle physics.

The center’s goals are to improve the performance and reduce the cost of accelerator technologies around the world and develop new research instruments that transform the frontiers of biology, materials science, condensed matter physics, particle physics and nuclear physics, as well as new manufacturing tools that enable chip makers to continue shrinking the features of integrated circuits.

“CBB has brought together a remarkably broad palette of researchers encompassing scientists from physics, physical chemistry, materials research, and accelerator science—an unusually diverse team that has the necessary skills and long-range vision to take on the challenge of helping the next-generation of accelerators come to fruition, with impact on many fields,” said Steven J. Sibener, the Carl William Eisendrath Distinguished Service Professor of Chemistry and the James Franck Institute at the University of Chicago, and a co-leader of CBB’s next-generation superconducting radio frequency materials research. “My role has been profoundly rewarding for my research group and for me personally, introducing us to new research directions in advanced superconducting materials design that will ultimately lead to the innovation of lower-cost accelerators with greatly improved brightness and performance.”

Opening up new fields in quantum chemistry and technology.

Researchers have big ideas for the potential of quantum technology, from unhackable networks to earthquake sensors. But all these things depend on a major technological feat: being able to build and control systems of quantum particles, which are among the smallest objects in the universe.

That goal is now a step closer with the publication of a new method by University of Chicago scientists. Published April 28 in Nature, the paper shows how to bring multiple molecules at once into a single quantum state—one of the most important goals in quantum physics.

"People have been trying to do this for decades, so we’re very excited,” said senior author Cheng Chin, a Professor of Physics and the James Franck Instiute who said he has wanted to achieve this goal since he was a graduate student in the 1990s. “I hope this can open new fields in many-body quantum chemistry. There’s evidence that there are a lot of discoveries waiting out there.”

Publication

Discovery addresses problem of generating and moving energy efficiently.

Three scientists from the Maziotti group in the JFI have run the numbers, and they believe there may be a way to make a material that could conduct both electricity and energy with 100% efficiency—never losing any to heat or friction.

The breakthrough, published Feb. 18 in Physical Review B, suggests a framework for an entirely new type of matter, which could have very useful technological applications in the real world. Though the prediction is based on theory, efforts are underway to test it experimentally.

“We started out trying to answer a really basic question, to see if it was even possible—we thought these two properties might be incompatible in one material,” said co-author and research adviser David Mazziotti, a professor of chemistry and the James Franck Institute and an expert in molecular electronic structure. “But to our surprise, we found the two states actually become entangled at a quantum level, and so reinforce each other.”

Graduate student LeeAnn Sager began to wonder how the two states could be generated in the same material. Mazziotti’s group specializes in exploring the properties and structures of materials and chemicals using computation, so she began plugging different combinations into a computer model. “We scanned through many possibilities, and then to our surprise, found a region where both states could exist together,” she said.

“Being able to combine superconductivity and exciton condensates would be amazing for lots of applications—electronics, spintronics, quantum computing,” said Shiva Safaei, a postdoctoral researcher and the third author on the paper. “Though this is a first step, it looks extremely promising.”

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Physics World

Breakthrough creates tough material able to stretch, heal and defend itself.

While eating takeout one day, James Franck Institute scientists Bozhi Tian and Yin Fang started thinking about the noodles—specifically, their elasticity. A specialty of Xi’an, Tian’s hometown in China, is wheat noodles stretched by hand until they become chewy—strong and elastic. Why, the two materials scientists wondered, didn’t they get thin and weak instead?

They started experimenting, ordering pounds and pounds of noodles from the restaurant. “They got very suspicious,” Fang said. “I think they thought we wanted to steal their secrets to open a rival restaurant.”

But what they were preparing was a recipe for synthetic tissue—that could much more closely mimic biological skin and tissue than existing technology.

“It turns out that granules of common starch can be the missing ingredient for a composite that mimics many of the properties of tissue,” said Fang, a UChicago postdoctoral researcher and lead author of a new paper published Jan. 29 in the journal Matter. “We think this could fundamentally change the way we can make tissue-like materials.”

The breakthrough allows the synthetic tissue to stretch in multiple directions but to heal and defend itself by reorganizing its internal structures —which is how human skin protects itself. The discovery could one day lead to applications from soft robotics and medical implants to sustainable food packaging and biofiltration.

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Current-constrained approach significantly improves upon prior methods.

The smaller and smarter that phones and devices become, the greater the need to build smaller circuits. Forward-thinking scientists in the 1970s suggested that circuits could be built using molecules instead of wires, and over the past decades that technology has become reality.

“Current models tend to overpredict conductance, but our theory outperforms traditional models by as much as one to two orders of magnitude,” said Prof. David Mazziotti, Professor of Chemistry and the James Franck Institute, who coauthored the paper, published May 31 in Nature’s Communications Chemistry.

“Almost all of the big problems that people are trying to solve involve working with materials that are difficult to explore with traditional methods,” he said. “If we can better predict the conductivity, we can more effectively design better molecules and materials.”

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Contact line deposits in an evaporating drop.

The year 2018 marks the 25th anniversary of Physical Review E. To celebrate the journal’s rich legacy, during the upcoming year we highlight a series of papers that made important contributions to their field. These milestone articles were nominated by members of the Editorial Board of Physical Review E, in collaboration with the journal’s editors. The 25 milestone articles, including an article for each calendar year from 1993 through 2017 and spanning all major subject areas of the journal, will be unveiled in chronological order and will be featured on the journal website.

For the year 2000, the following collaborative work from three groups in the James Franck Institute is featured:

Contact line deposits in an evaporating drop
Robert D. Deegan, Olgica Bakajin, Todd F. Dupont, Greg Huber, Sidney R. Nagel, and Thomas A. Witten
Phys. Rev. E 62, 756 (2000)

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Study examines how to manipulate photons for quantum engineering.

Quantum systems behave according to the strange laws that govern the smallest particles in the universe, like electrons. Scientists are increasingly interested in exploring new ways to harness the particles’ odd behaviors, like being in two states at once, and then choosing one only when measured.

Jonathan Simon, the Neubauer Family Assistant Professor of Physics and the James Franck Institute, is interested in how walls dividing matter and light begin to break down at this scale. Most electronic systems use electrons as the moving parts, but photons can display quantum properties just as easily as electrons—and photons’ quirks could both offer advantages as technologies and serve as models to understand the more slippery electrons. So his team wants to manipulate and stack photons to build matter out of light.

“Essentially we want to make photon systems into a kind of quantum Legos—blown-up materials that you can more easily study and tease out basic quantum design principles,” said Simon, who is also a fellow of the Institute for Molecular Engineering.

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Amorphous topological insulators constructed from random point sets.

Using a set of gyroscopes linked together, physicists explored the behavior of a material whose structure is arranged randomly, instead of an orderly lattice. They found they could set off one-way ripples around the edges, much like spectators in a sports arena—a “topological wave,” characteristic of a particularly unusual state of matter.

Published Jan. 15 in Nature Physics, the discovery offers new insight into the physics of collective motion and could one day have implications for electronics, optics or other technologies.

The team, led by Assoc. Prof. William Irvine, used gyroscopes—the top-like toys you played with as a kid—as a model system to explore physics. Because gyroscopes move in three dimensions, if you connect them with springs and spin them with motors, you can observe all kinds of things about the rules that govern how objects move together.

“Everything up to this point was engineered. We thought you had to build a particular lattice, and that determines where the wave goes,” said Irvine. “But when we asked what happened if you took away the spatial order, no crystal plane, no clear structure…the answer’s yes. It just works.”

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Observe particles acting coherently as they undergo phase transitions.

A study published Dec. 18 in Nature Physics by University of Chicago scientists observed how particles behave as the change takes place in minute detail. In addition to shedding light on the fundamental rules that govern the universe, understanding such transitions could help design more useful technologies.

One of the questions was whether, as particles prepare to transition between quantum states, they can act as one coherent group that “knows” the states of the others, or whether different particles only act independently of one another, or incoherently.

Cheng Chin, Professor in the James Franck Institute and Department of Physics, and his team looked at an experimental setup of tens of thousands of atoms cooled down to near absolute zero. As the system crossed a quantum phase transition, they measured its behavior with an extremely sensitive imaging system.

The conventional wisdom was that the atoms should evolve incoherently after the transition--a hallmark of older “classic” rather than quantum models of physics. “In contrast, we found strong evidence for coherent dynamics,” said graduate student Lei Feng, the first author on the study. “In no moment do they become classical particles; they always behave as waves that evolve in synchrony with each other, which should give theorists a new ingredient to include in how they model such systems that are out of equilibrium.”

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Demonstrates the power of modern computing for simulating viruses.

Computer modeling has helped a team of scientists, including several scholars from the the Voth group in the JFI, to decode previously unknown details about the process by which HIV forces cells to spread the virus to other cells. The findings, published Nov. 7 in Proceedings of the National Academy of Sciences, may offer a new avenue for drugs to combat the virus.

A key part of HIV’s success is a nasty little trick to propagate itself inside the body. Once HIV has infected a cell, it forces the cell to make a little capsule out of its own membrane, filled with the virus. The capsule pinches off—a process called “budding”—and floats away to infect more cells. Once inside another unsuspecting cell, the capsule coating falls apart, and the HIV RNA gets to work.

Scientists knew that budding involves an HIV protein complex called Gag protein, but the details of the molecular process were murky. “For a while now we have had an idea of what the final assembled structure looks like, but all the details in between remained largely unknown,” said Gregory Voth, the Haig P. Papazian Distinguished Service Professor of Chemistry and corresponding author on the paper.

Since it’s been difficult to get a good molecular-level snapshot of the protein complex with imaging techniques, Voth and his team built a computer model to simulate Gag in action. Simulations allowed them to tweak the model until they arrived at the most likely configurations for the molecular process, which was then validated by experiments in the laboratory of Jennifer Lippincott-Schwartz at the National Institutes of Health and the Howard Hughes Medical Institute Janelia Research Campus.

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