News

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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Recognition for Laurie Butler, Heinrich Jaeger, and Andrei Tokmakoff.

Laurie Butler is a Professor of chemistry with the James Frank Institute. She investigates fundamental inter- and intramolecular forces that drive the courses of chemical reactions, integrating our understanding of quantum mechanics into chemistry. Among other applications, her current work has implications for our models of atmospheric and combustion chemistry. She is a fellow of the American Physical Society and a former Alfred P. Sloan Fellow.

Heinrich Jaeger is the Sewell L. Avery Distinguished Service Professor in the Department of Physics and the James Franck Institute. His laboratory studies the investigation of materials under conditions far from equilibrium, especially to design new classes of smart materials. A focus of Jaeger’s work are granular materials, which are large aggregates of particles in far-from-equilibrium configurations, that exhibit properties intermediate between those of ordinary solids and liquids – which could lead to everything from soft robotic systems that can change shape to new forms of architectural structures that are fully recyclable. He is a former Fulbright Scholar and Alfred P. Sloan Research Fellow and is currently a fellow of the American Physical Society.

Andrei Tokmakoff is the Henry J. Gale Distinguished Service Professor of Chemistry with the James Franck Institute. He studies the chemistry of water, and molecular dynamics of biophysical processes such as protein folding and DNA hybridization. His lab uses advanced spectroscopy to visualize how molecular structure changes with time to study these problems. He was an Alfred P. Sloan Fellow and has received the American Physical Society’s Ernest Plyler Prize, among others.

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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Professor Emeritus of Physics in the James Franck Institute.

Dean Eastman, Director of Argonne from 1996-1998 and Professor Emeritus of Physics in the James Franck Institute at the University of Chicago, died on March 4, 2018, at the age of 78. His tenure at Argonne lab saw the Advanced Photon Source begin its operations and the Gammasphere (part of the Argonne Tandem Linac Accelerator System) make its first move from Lawrence Berkeley National Laboratory to Argonne.

After receiving three degrees from the Massachusetts Institute of Technology, Eastman had a successful career as a research physicist with IBM, working at the Thomas J. Watson Research Center in Yorktown Heights, New York. He became a world-renowned expert on the electronic properties of materials and spectroscopy and vice president of technical strategy and development reengineering, IBM Server Group.

His passion for building and architecture led to his restoration of Frank Lloyd Wright’s Avery Coonley House in Riverside, Illinois. Eastman self-published “Frank Lloyd Wright’s Coonley House Estate: An Unabridged Documentary,” a book detailing the restoration.

Born in Oxford, Wisconsin, Eastman grew up in the Upper Peninsula of Michigan.

He was a member of the National Academy of Sciences, the National Academy of Engineering, the American Academy of Arts and Sciences, and an honorary member of the American Institute of Architects.

He is survived by his wife and two brothers.

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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Prestigious early-career recognition.

Tim Berkelbach, a Neubauer Family Assistant Professor, is a theoretical chemist who studies the electronic and optical properties of nanoscale materials. His group adapts computational models written for tens of atoms and scales them up to work for sets of hundreds or thousands—which you need to model materials for applications in solar energy, catalysis and manufacturing, chemical sensing and electronics.

“It’s an honor to be selected, especially alongside such an amazing lineup of people who have been recognized as Sloan fellows over the years,” Berkelbach said.

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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Reveals new form of spontaneous quantum scattering in a driven many-body system.

“This is a very fundamental behavior that we have never seen before; it was a great surprise to us,” said study author Cheng Chin, Professor of Physics and in the JFI. Published Nov. 6 in Nature, the research details a curious phenomenon — seen in what was thought to be a well-understood system — that may someday be useful in quantum technology applications.

Chin’s lab studies what happens to particles called bosons in a special state called a Bose-Einstein condensate. When cooled down to temperatures near absolute zero, bosons will all condense into the same quantum state. Researchers applied a magnetic field, jostling the atoms, and they began to collide—sending some flying out of the condensate. But rather than a uniform field of random ejections, they saw bright jets of atoms shooting together from the rim of the disk, like miniature fireworks.

The tiny jets may show up in other systems, researchers said and understanding them may help shed light on the underlying physics of other quantum systems.

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Recognized by ETH Zürich at Materials Day 2017 meeting.

The ETH Materials Research Prize for Young Investigators recognizes outstanding contributions of young investigators that advance materials, from fundamental to applied research. These contributions could include, for example: the discovery of new classes of materials, the observation of novel phenomena leading to either fundamentally new applications and insights, and work that substantially impacts our understanding or applications of existing materials and phenomena.

Bozhi Tian, Assistant Professor at the University of Chicago, triumphed over stiff competition. Tian researches interactions between biological and electronic systems; for example, he examines how the behaviour of cells can be mimicked with semiconducting nanomaterials or how special nanomaterials can be used to measure the electrical conductivity of cells.

“Tian combines hard and soft materials in his research and connects the living with the lifeless,” explains Ralph Spolenak, Professor of Nanometallurgy and Head of the Department of Materials at ETH Zürich. “The bridge between these two poles is a major area in today’s materials science, one that is not only important for medicine, but also enables interesting applications in many other areas.”

Utilizing gas-surface collisions on patterned silicon.

In a paper published in Physical Review Letters, a team led by Prof. Steven J. Sibener describes a way to separate isotopes of neon using a beam of gas aimed at a precisely patterned silicon wafer, which reflects the different isotopes at slightly different angles. The method could one day be a less costly and more energy-efficient way to separate isotopes for medicine, electronics and other applications.

“One can think about it like separating the various colors of light into a rainbow using a prism,” said Sibener, the Carl William Eisendrath Distinguished Service Professor of Chemistry and the James Franck Institute. “This is a wonderful and very precise demonstration study, and we are very pleased with the results,” Sibener said. “It has been a delight to run down to the lab every day to see what’s happened. We’re very much looking forward to planning the next steps in this project to explore other atoms and molecules.”

Viewpoint
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For experiments and theory on the topological aspects of fluid dynamics and mechanical metamaterials.

William Irvine was recently elected a Fellow of the American Physical Society, nominated by the Topical Group on Soft Matter. The criterion for APS Fellow election is exceptional contributions to the physics enterprise; e.g., outstanding physics research, important applications of physics, leadership in or service to physics, or significant contributions to physics education. Fellowship is a distinct honor signifying recognition by one's professional peers.

Research for the Irvine group was recently featured on the cover of Physics Today. The Irvine Group at the University of Chicago has put a new twist on the smoke ring. Instead of blowing smoke into the air to create and visualize swirling flows known as vortex rings, they drove 3D-printed hydrofoils, lined with fluorescent dye, through water. Here, the wispy outer ring of white dye reveals a vortex ring; the orange and green trails are a tomographic reconstruction of the ring’s evolution over time. To learn how the group’s technique helped unveil hidden structure in fluid vortices, see the story.

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Awarded for Study of Exciton Interactions in Semiconductor Nanostructures.

The Young Investigator Program is open to scientists and engineers at research institutions across the United States who received Ph.D. or equivalent degrees in the last five years and who show exceptional ability and promise for conducting basic research. The objective of this program is to foster creative basic research in science and engineering, enhance early career development of outstanding young investigators, and increase opportunities for the young investigators to recognize the Air Force mission and the related challenges in science and engineering.

Layer-by-layer assembly of two-dimensional materials into wafer-scale heterostructures.

In a study published Sept. 20 in Nature, UChicago and Cornell University researchers describe an innovative method to make stacks of semiconductors just a few atoms thick. The technique offers scientists and engineers a simple, cost-effective method to make thin, uniform layers of these materials, which could expand capabilities for devices from solar cells to cell phones.

“The scale of the problem we’re looking at is, imagine trying to lay down a flat sheet of plastic wrap the size of Chicago without getting any air bubbles in it,” said Jiwoong Park, a UChicago professor in the Department of Chemistry, the Institute for Molecular Engineering and the James Franck Institute, who led the study. “When the material itself is just atoms thick, every little stray atom is a problem. We expect this new method to accelerate the discovery of novel materials, as well as enabling large-scale manufacturing,” Park said.