Galitski Research Group

Normally the word “chaos” evokes a lack of order: a hectic day, a teenager’s bedroom, tax season. And the physical understanding of chaos is not far off. It’s something that is extremely difficult to predict, like the weather. Chaos allows a small blip (the flutter of a butterfly wing) to grow into a big consequence (a typhoon halfway across the world), which explains why weather forecasts more than a few days into the future can be unreliable. Individual air molecules, which are constantly bouncing around, are also chaotic—it’s nearly impossible to pin down where any single molecule might be at any given moment.

The quantum world blatantly defies intuitions that we’ve developed while living among relatively large things, like cars, pennies and dust motes. The quantum behavior of dynamical localization bucks the assumption that a cold object will always steal heat from a warmer object. Until now, dynamical localization has only been observed for single quantum objects, which has prevented it from contributing to attempts to pin down where the changeover occurs. JQI researchers and colleagues have investigated mathematical models to see if dynamical localization can still arise when many quantum particles interact. To reveal the physics, they had to craft models to account for various temperatures, interaction strengths and lengths of times. The team’s results, published in Physical Review Letters, suggest that dynamical localization can occur even when strong interactions are part of the picture.

Researchers at the University of Maryland have captured the most direct evidence to date of a quantum quirk that allows particles to tunnel through a barrier like it’s not even there. The result, featured on the cover of the June 20, 2019 issue of the journal Nature, may enable engineers to design more uniform components for future quantum computers, quantum sensors and other devices. The new experiment is an observation of Klein tunneling, a special case of a more ordinary quantum phenomenon. In the quantum world, tunneling allows particles like electrons to pass through a barrier even if they don’t have enough energy to actually climb over it. A taller barrier usually makes this harder and lets fewer particles through.Klein tunneling occurs when the barrier becomes completely transparent, opening up a portal that particles can traverse regardless of the barrier’s height. Scientists and engineers from UMD’s Center for Nanophysics and Advanced Materials (CNAM), the Joint Quantum Institute (JQI) and the Condensed Matter Theory Center (CMTC), with appointments in UMD’s Department of Materials Science and Engineering and Department of Physics, have made the most compelling measurements yet of the effect.

Seventeen theoretical physics faculty across 12 institutions have established a new Simons Collaboration on Ultra-Quantum Matter. The team, which includes Victor Galitski, a Chesapeake Chair Professor of Theoretical Physics in the Department of Physics and Fellow of the Joint Quantum Institute, will investigate innovative ideas about how quantum physics works on macroscopic scales. This new effort will be led by Professor Ashvin Vishwanath at Harvard University and is supported under the Simons Collaborations in Mathematics and Physical Sciences program, which aims to “stimulate progress on fundamental scientific questions of major importance in mathematics, theoretical physics and theoretical computer science."

A powerful engine roils deep beneath our feet, converting energy in the Earth’s core into magnetic fields that shield us from the solar wind. Similar engines drive the magnetic activity of the sun, other stars and even other planets—all of which create magnetic fields that reinforce themselves and feed back into the engines to keep them running. Much about these engines, which scientists refer to as dynamos, remains unknown. That’s partly because the math behind them is doubly difficult, combining the complex equations of fluid motion with the equations that govern how electric and magnetic fields bend, twist, interact and propagate. But it’s also because lab-bound dynamos, which attempt to mimic the astrophysical versions, are expensive, dangerous and do not yet reliably produce the signature self-sustaining magnetic fields of real dynamos. Now, Victor Galitski, a Fellow of the Joint Quantum Institute (JQI), in collaboration with two other scientists, has proposed a radical new approach to studying dynamos, one that could be simpler and safer. The proposal, which was published Oct. 25 in Physical Review Letters, suggests harnessing the electrons in a centimeter-sized chunk of solid matter to emulate the fluid flows in ordinary dynamos.