报告题目：Higher-order Weyl-Exceptional-Ring Semimetal

报告人：刘涛教授  华南理工大学

报告时间：2021年5月27日（周四） 10：00

报告地点：理6栋302    邀请人：郎利君

报告内容：

      Recently, considerable efforts have been devoted to explore topological phases in non-Hermitian extensions of topological insulators and semimetals. Non-Hermiticity originates from dissipation in open classical and quantum systems, leading to novel topological phases without Hermitian counterparts. One of its salient characteristics is the emergence of exceptional points, i.e., non-Hermitian band degeneracies at which eigenstates coalesce. Noticeably, the non-Hermiticity can alter the nodal structures (i.e., band degeneracies in Hermitian topological semimetals), where exceptional points form new types of topological semimetals. In this talk, I will start with an overview of non-Hermitian phenomena and higher-order topological phases, then present our recent theoretical proposal to realize non-Hermitian higher-order topological semimetals, where we have identified a new type of bulk-band degeneracies, i.e., Weyl exceptional rings in higher-order topological phases.

专家简介：

      刘涛，华南理工大学物理与光电学院教授，博士生导师。2014 年博士毕业于新加坡南洋理工大学，其后分别在新加坡南洋理工大学和日本理化学研究所从事博士后研究，2018年获日本学术振兴会外国人特别研究员 (JSPS Postdoctoral Fellowship) 。研究方向涉及拓扑物态、非厄米系统物理学以及强关联多体量子系统。已在Physical Review Letters, Nature Communications, Physical Review B, Applied Physics Letters, Optics Express等期刊发表论文30余篇，其中高被引论文2篇。