Irvine group measures intertwining vortices in laboratory
Clever experiment documents multi-scale fluid dynamics
The new findings, published Aug. 3 in Science, are the first to show that helicity maintains a constant value during the flow of viscous fluids. Vortex dynamics have important applications in everyday life; meteorologists, for example, view helicity as a factor that contributes to the formation of supercell tornadoes.
“The fact that we have some measurements for the first time that show helicity can be preserved, especially in the presence of stretching, can translate directly to those efforts,” said William Irvine, an Associate Professor of Physics in the James Franck Institute, who published the findings along with four co-authors.
Simulating helicity in those flows has been difficult because of the widely separated yet interconnecting scales in which they operate. Previous work had been largely theoretical and involved hypothetical, simpler fluids totally lacking in viscosity. Calculations showed that helicity was conserved in these hypothetical fluids, but viscosity emerged as a significant factor in the flow of actual fluids.
“One of the core problems is that you need to sample or measure features of the flow that exist on very different length scales,” said Martin Scheeler, the study’s lead author, who recently completed his Doctorate in Physics in the JFI. The scales range from the diameter of a vortex (approximately 30 centimeters or one foot) to the diameter of its thin core (approximately one milllimeter or three hundredths of an inch).
“You need to measure the flow inside the core as well as the overall shape evolution of that vortex,” Irvine said. “That’s quite a separation.” Irvine characterized Scheeler’s work in overcoming the experimental challenges— simultaneously tracking the fine details of the flow while still measuring the critical larger-scale dynamics—as “a tour de force.”
Arvind Murugan receives 2017 Simons Investigator award
For research in Mathematical Modeling of Living Systems
Arvind Murugan works on how organisms enhance information uptake from the environment by using inference from past experience and has applied such ideas to self-assembly dynamics, olfaction, circadian clocks and stress-response pathways. The Simons Investigators program provides a stable base of support for outstanding scientists, enabling them to undertake long-term study of fundamental questions.
Talapin group develops DOLFIN approach to build nanomaterials into electronic devices
New method promises easier nanoscale manufacturing
The new research, published in Science, is expected to make such materials easily available for eventual use in everything from LED displays to cellular phones to photodetectors and solar cells. Though nanomaterials are promising for future devices, ways to build them into complex structures have been limited and small-scale.
“This is a step needed to move quantum dots and many other nanomaterials from proof-of-concept experiments to real technology we can use,” said co-author Dmitri Talapin, Professor of Chemistry in the James Franck Institute and Scientist with the Center for Nanoscale Materials at Argonne. “It really expands our horizons.”
The new technique, called DOLFIN, makes different nanomaterials directly into “ink” in a process that bypasses the need to lay down a polymer stencil. Talapin and his team carefully designed chemical coatings for individual particles. These coatings react with light, so if you shine light through a patterned mask, the light will transfer the pattern directly into the layer of nanoparticles below—wiring them into useful devices.
“We found the quality of the patterns was comparable to those made with state-of-the-art techniques,” said lead author Yuanyuan Wang, postdoctoral researcher in the Talapin group. “It can be used with a wide range of materials, including semiconductors, metals, oxides or magnetic materials—all commonly used in electronics manufacturing.”
The team is working toward commercializing the DOLFIN technology in partnership with UChicago’s Polsky Center for Entrepreneurship and Innovation.
Vincenzo Vitelli to join Faculty
Arriving in Autumn 2017
The JFI is pleased to welcome the Vitelli group to campus in Autumn 2017.
Chin group settle debate over how exotic quantum particles form
Implications for universality
New research by physicists at the University of Chicago settles a longstanding disagreement over the formation of exotic quantum particles known as Efimov molecules. The findings, published last month in Nature Physics, address differences between how theorists say Efimov molecules should form and the way researchers say they did form in experiments. The study found that the simple picture scientists formulated based on almost 10 years of experimentation had it wrong—a result that has implications for understanding how the first complex molecules formed in the early universe and how complex materials came into being.
“I have to say that I am surprised,” Chin said. “This was an experiment where I did not anticipate the result before we got the data.”
The data came from extremely sensitive experiments done with cesium and lithium atoms using techniques devised by Jacob Johansen, previously a graduate student in Chin’s lab who is now a postdoctoral fellow at Northwestern University. Krutik Patel, a graduate student at UChicago, and Brian DeSalvo, a postdoctoral researcher at UChicago, also contributed to the work.
JaegerFest: In Honor of Heinrich Jaeger's 60th Birthday
The World in a Grain of Sand: A Symposium on the Collective Behavior of Particles
In honor of Heinrich Jaeger’s 60th birthday and to celebrate his highly productive and inspiring scientific career, the MRSEC, JFI, and Physics Department hosted a special Symposium on June 2-3. JaegerFest welcomed to campus more than 100 friends, colleagues, staff and administrators both current and retired, as well as many generations of current and former graduate students. Participants enjoyed a full day of talks related to granular physics, and dinner at the local Experimental Station that included a "roast" where everyone could only think of nice things to say.
Suri Vaikuntanathan awarded Sloan Research Fellowship
Prestigious early-career recognition
The Sloan Research Fellows are the rising stars of the academic community,” says Paul L. Joskow, President of the Alfred P. Sloan Foundation. “Through their achievements and ambition, these young scholars are transforming their fields and opening up entirely new research horizons. We are proud to support them at this crucial stage of their careers.”
New method uses heat flow to levitate variety of objects
Undergraduates in Chin group lead breakthrough work
Third-year Frankie Fung and fourth-year Mykhaylo Usatyuk led a team of UChicago researchers who demonstrated how to levitate a variety of objects—ceramic and polyethylene spheres, glass bubbles, ice particles, lint strands and thistle seeds—between a warm plate and a cold plate in a vacuum chamber.
“They made lots of intriguing observations that blew my mind,” said Cheng Chin, professor of physics, whose ultracold lab in the Gordon Center for Integrative Science was home to the experiments.
New SPIFF method improves accuracy of imaging systems
Collaborative work by the Dinner, Rice, and Scherer groups
The newly developed SPIFF (single-pixel interior filling function) method provides a way to detect and correct systematic errors in data and image analysis used in many areas of science and engineering.
“Anyone working with imaging data on tiny objects — or objects that appear tiny — who wants to determine and track their positions in time and space will benefit from the single-pixel interior filling function method,” said co-principal investigator Norbert Scherer.
Myford Super 7 lathe dedication
New tool for the JFI Student Machine Shop
Stuart Rice generously donated a Myford Super 7 Lathe to the JFI Student Machine Shop, and we had a dedication ceremony on January 10, 2017. The lathe is already being put to good use.
Prof. Robert Gomer, 1924-2016
Former JFI Director and pioneering chemist passes away at the age of 92.
Prof. Emeritus Robert Gomer, a chemical physicist who pioneered techniques for studying molecules and taught at the University of Chicago for nearly a half-century, died Dec. 12 of complications related to Parkinson’s disease. He was 92.
Chin group confirms theory describing principles of phase transitions
Ultracold atoms unveil a universal symmetry of systems crossing continuous phase transitions
For systems near continuous phase transitions, the details don’t matter. In principle, a universal theory can be applied to understand continuous phase transitions whether they occur in biological cell membranes, magnets, liquid crystals, or even in the entire early universe! But while the universal theory of static systems near continuous phase transitions has been generally successful, the degree to which the dynamics of crossing such transitions can be universally explained presents an exciting new frontier.
Recent work by the Chin group uncovers these universal features in the dynamics of ultracold atoms in a shaking optical lattice. When the researchers shake the lattice they find that atoms undergo a continuous, quantum phase transition, after which they must choose between two new ground states with either leftward or rightward momentum. This causes the gas to split into domains with atoms in one momentum state or the other, which can then be observed using a microscope. The researchers found that the details are indeed irrelevant: the growth of domains over time and their pattern across space are independent of the rate at which the transition is crossed, once they account for a simple power-law scaling of space and time. These findings support the universal scaling symmetry of phase transition dynamics, which provides a simple, powerful prediction for the behavior of a huge variety of systems when they cross continuous phase transitions.
Heinrich Jaeger receives 2016 Faculty Award for Excellence in Graduate Teaching and Mentoring
When it comes to graduate education, it’s the questions that concern Heinrich Jaeger, not the answers.
“Many students might think that we would be very much laboring to find answers to big questions, and that is certainly true,” says Jaeger. “But the important aspect of mentoring is to find questions. How do you bring students to the point that they will ask research questions that are interesting and important?”
New Device Steps Toward Isolating Single Electrons for Quantum Computing
The Schuster Group has integrated trapped electrons with superconducting quantum circuits
“A key aspect of this experiment is that we have integrated trapped electrons with more well-developed superconducting quantum circuits,” said graduate student Ge Yang, lead author of the Physical Review X paper that reported the group’s findings. The team captured the electrons by coaxing them to float above the surface of liquid helium at extremely low temperatures.