Quantum Many-Body Physics Beyond Ground States

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Date/Time:Monday, 25 Feb 2019 from 4:10 pm to 5:00 pm
Location:Phys 0003
Phone:515-294-5441
Channel:College of Liberal Arts and Sciences
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Dr. Thomas Iadecola, University of Maryland

Abstract

The last few decades have given rise to a new perspective on the statistical mechanics of isolated quantum many-body systems. This perspective prioritizes quantum entanglement as a central measure of the thermal or athermal nature of a generic (i.e. highly excited) quantum state. Recently, the concept of many-body localization (MBL) has emerged as a prominent alternative to thermalization wherein the rules of statistical mechanics do not apply. After reviewing these ideas, I will present two recent examples from my own work that highlight ways in which the thermal/MBL dichotomy is insufficient to characterize the full richness inherent in highly excited states of quantum many-body systems. First, I will show how strongly disordered quantum many-body systems can host thermal and athermal eigenstates at the same energy density, leading to a so-called "mobility emulsion." Second, I will discuss "quantum many-body scars," a novel phenomenon observed in recent experiments wherein certain initial conditions fail to equilibrate on experimental timescales, contrary to expectations based on statistical mechanics. I will suggest a new picture of this phenomenon wherein the observed coherent dynamics emerges from correlations among elementary low-energy excitations.

Bio

Dr. Iadecola is a JQI Postdoctoral Fellow at the University of Maryland. He completed his doctoral studies in physics at Boston University under the supervision of Claudio Chamon, and his undergraduate studies in Mathematics-Physics at Brown University. His work in quantum condensed matter theory focuses on out-of-equilibrium phenomena in quantum many-body systems, on topological phases of matter, and on connections between the two.