Fractionalized conductivity and emergent self-duality near topological phase transitions
报告人（单位）
William Witczak-Krempa (University of Montreal, Canada)
报告时间
2022年6月14日 9:00
主办方
蔻享学术
直播二维码
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报告人介绍
Dr. William Witczak-Krempa is a condensed matter theorist and is interested in the unusual states of matter that emerge (usually) at low temperature, where quantum mechanics dictates the rules. William is currently an Associate Professor of University of Montreal, Quebec in Canada. William got B.Sc. in McGill University in 2007 and PhD in University of Toronto in 2012. During 2012-2015, William was employed as a Postdoctoral Fellow in Perimeter Institute for Theoretical Physics. During 2015-2016, William was a postdoctoral fellow in Prof. Subir Sachdev’s research group in Harvard University. Since 2016, William has become a faculty member of University of Montreal.
报告摘要
The experimental discovery of the fractional Hall conductivity in two-dimensional electron gases revealed new types of quantum particles, called anyons, which are beyond bosons and fermions as they possess fractionalized exchange statistics. These anyons are usually studied deep inside an insulating topological phase. It is natural to ask whether such fractionalization can be detected more broadly, say near a phase transition from a conventional to a topological phase. To answer this question, we study a strongly correlated quantum phase transition between a topological state, called a Z2 quantum spin liquid, and a conventional superfluid using large-scale quantum Monte Carlo simulations. Our results show that the universal conductivity at the quantum critical point becomes a simple fraction of its value at the conventional insulator-to-superfluid transition. Moreover, a dynamically self-dual optical conductivity emerges at low temperatures above the transition point, indicating the presence of the elusive vison particles. Our study opens the door for the experimental detection of anyons in a broader regime, and has ramifications in the study of quantum materials, programmable quantum simulators, and ultra-cold atomic gases. In the latter case, we discuss the feasibility of measurements in optical lattices using current techniques. Ref: Wang, YC., Cheng, M., Witczak-Krempa, W. et al., Nat Commun 12, 5347 (2021).