报告题目：Berezinskii-Kosterlitz-Thouless-like localization-localization transitions in disordered two-dimensional second-order topological insulators

报告人： 汪晨 副教授（天津大学）

报告时间：2023年09月15日（星期五）14：00-15：30

报告地点：北洋园校区 49 教 210 室（腾讯会议：516-8729-1333）

报告摘要：

Anderson localization transitions are quantum phase transitions from delocalized to localized states in disordered systems. In this talk, I report an unconventional “Anderson localization transition” in two-dimensional quantized quadrupole insulators. Such transitions are from symmetry-protected topological corner states to disorder-induced typical Anderson localized states that can be localized in bulk and at corners and edges. We show that these localization-localization transitions (transitions between two different localized states) can happen in Hermitian and non-Hermitian quantized quadrupole insulators and investigate their criticality by finite-size scaling analysis of the corner density. The scaling analysis suggests that the correlation length of the phase transition, on the Anderson insulator side, and near critical disorder, diverges exponentially. This is a typical feature of Berezinskii-Kosterlitz-Thouless transitions. A map from the quantized quadrupole model to the quantum two-dimensional XY model hints at why the localization-localization transitions are Berezinskii-Kosterlitz-Thouless type.

报告人简介：

Dr. Chen WANG received his Ph.D. degree from Hong Kong University of Science and Technology in 2016 and joined the department of science of Tianjin University in 2019. His research interests include quantum phase transitions induced by disorders, topological phases, spintronics, and quantum chaos. Recently, he has focused on exploring novel phenomena in non-Hermitian systems.

参考文献：

[1] arXiv: 2306.08813 (2023).