主讲人：贾伟 博士（北京大学）

题目：Unified characterization for higher-order topological phase transitions

时间：2023年03月15日（周三）上午9：00

地址：理工楼1226报告厅

报告摘要：

Higher-order topological phase transitions (HOTPTs) are associated with closing either the bulk energy gap (type-I) or boundary energy gap (type-II) without changing symmetry, and conventionally the both transitions are captured in real space and characterized separately. Here we propose a momentum-space topological characterization of the HOTPTs, which unifies the both types of topological transitions and enables a precise detection by quench dynamics. Our unified characterization is based on a novel correspondence between the mass domain walls on real-space boundaries and the higher-order band-inversion surfaces (BIS) which are characteristic interfaces in the momentum subspace. The topological transitions occur when momentum-space topological nodes, dubbed higher-order topological charges, cross the higher-order BISs after proper projection. Particularly, the bulk (boundary)gap closes when all (part of) topological charges cross the BISs, characterizing the type-I (type-II) HOTPTs. This scheme can be feasibly measured from quench dynamics driven with control in experiments. Our work opens an avenue to characterize and detect the two types of HOTPTs within a unified framework, and shall advance the research in both theory and experiment.

参考文献：W. Jia, X. C. Zhou, L. Zhang, L. Zhang, and X.-J. Liu, arXiv:2209.10394

个人简介：

贾伟，2008-2015 年西北师范大学本科、硕士。2015-2019 年北京理工大学博士。2019-2021年北京大学博雅博士后。2021-至今北京大学博士后。目前研究方向为非平衡量子系统中的拓扑物理。已在 Sci. Bull. ，Phys. Rev. A/ B ，New J. Phys.等期刊发表学术论文十余篇。