时间：2021年10月21日（星期四）16:00-17:30
地点：4#211
主持人：吴从军教授
主讲人：叶锦武教授，美国密西西比州立大学
报告题目：Bose-Einstein condensations of magnons in quantum magnets with spin-orbit coupling
主讲人简介：
Jinwu Ye received his Ph.D. degree from Yale University. He is the professor at Mississippi State University. Currently, He is a long-term visitor at Institute for Theoretical Sciences at Westlake University. His two most recent research directions are on
(1) Topological Phases, topological phase transitions driven by interactions in various spin-orbit coupled systems.
(2) Quantum chaos and quantum information scramblings in cavity QED systems or in Sachdev-Ye-Kitaev (SYK) models. Connections among SYK models, conformal field theory, quantum gravity and topological phases.
报告摘要：
We study the response of a quantum magnet with spin-orbit coupling (SOC) to a Zeeman field and find novel classes of quantum phase transitions driven by the magnon condensations at commensurate (C-) or in-commensurate (IC-) momenta. We identify a new type of dangerously irrelevant operator which is irrelevant near the transition, does not change the symmetry breaking ground state, but changes its excitation spectrum to an exotic form. We name the new one Type-II dangerously irrelevant operator in contrast to the previously known one which we name Type-I. We derive the relations between the quantum spin and the order parameters of the effective actions which is crucial to determine the spin-orbital structures of all these quantum phases. The intrinsic differences between the magnon condensations at the C- and IC- momenta are explored. The experimental implications to cold atoms or materials with SOC are presented.
