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The research of JQI Fellow Alicia Kollár, who is also a Chesapeake Assistant Professor of Physics at the University of Maryland, embodies the give and take between physics and mathematics. In her lab, she brings abstract theories to life and in turn collaborates on new theorems. She has forged a research program of manipulating light on a chip, coaxing the light into behaving as though it lives on the surface of a sphere, or a mathematical abstraction known as a hyperbolic surface. She also collaborates with mathematicians, furthering both the understanding of what these chips can do and their underlying mathematics. A direct collaboration with pure mathematicians is uncommon for a physicist, particularly an experimentalist. But Kollár is no stranger to mathematics.

There is nothing permanent except change. This is perhaps never truer than in the fickle and fluctuating world of quantum mechanics. The quantum world is in constant flux. The properties of quantum particles flit between discrete, quantized states without any possibility of ever being found in an intermediate state. How quantum states change defies normal intuition and remains the topic of active debate—for both scientists and philosophers. The rules governing things like billiards balls and the temperature of a gas look very different from the quantum rules governing things like electron collisions and the energy absorbed or released by a single atom. And there is no known sharp, defining line between these two radically different domains of physical laws. Quantum changes are foundational to our universe and understanding them is becoming increasingly important for practical applications of quantum technologies. In a paper published Feb. 28, 2022 in the journal Physical Review X, JQI Fellow Alexey Gorshkov, JQI postdoctoral researcher Luis Pedro García-Pintos and their colleagues provide a new perspective for investigating quantum changes. They developed a mathematical description that sorts quantum behaviors in a system into two distinct parts. One piece of their description looks like the behavior of a quantum system that isn’t interacting with anything, and the second piece looks like the familiar behavior of a classical system. Using this perspective, the researchers identified limits on how quickly quantum systems can evolve based on their general features, and they better describe how those changes relate to changes in non-quantum situations.

JQI Fellow Alicia Kollár has been awarded a prestigious 2022 Sloan Research Fellowship. This award is given to early career researchers by the Alfred P. Sloan Foundation to recognize distinguished performance and the potential to make substantial contributions to their field. Each fellowship provides $75,000 to support the fellow’s research over two years.

Often when physicists study phases of matter they examine how a solid slab of metal or a cloud of gas changes as it gets hotter or colder. Sometimes the changes are routine—we’ve all boiled water to cook pasta and frozen it to chill our drinks. Other times the transformations are astonishing, like when certain metals get cold enough to become superconductors or a gas heats up and breaks apart into a glowing plasma soup. However, changing the temperature is only one way to transmute matter into different phases. Scientists also blast samples with strong electric or magnetic fields or place them in special chambers and dial up the pressure. In these experiments, researchers are hunting for a stark transition in a material’s behavior or a change in the way its atoms are organized. In a new paper published recently in the journal Physical Review Letters, Barkeshli and two colleagues continued this tradition of exploring how materials respond to their environment. But instead of looking for changes in conductivity or molecular structure, they focused on changes in a uniquely quantum property: entanglement, or the degree to which quantum particles give up their individuality and become correlated with each other.