Anomalous Transport Induced by Non-Hermitian Anomalous Berry Connection in Non-Hermitian Systems  

作　　者：Jiong-Hao Wang Yu-Liang Tao Yong Xu 王炅昊;陶禹良;徐勇(Center for Quantum Information,IIIS,Tsinghua University,Beijing 100084,China;Shanghai Qi Zhi Institute,Shanghai 200030,China)

机构地区：[1]Center for Quantum Information,IIIS,Tsinghua University,Beijing 100084,China [2]Shanghai Qi Zhi Institute,Shanghai 200030,China

出　　处：《Chinese Physics Letters》2022年第1期1-6,共6页中国物理快报（英文版）

基　　金：supported by the National Natural Science Foundation of China(Grant No. 11974201);the Start-up Fund from Tsinghua University。

摘　　要：Non-Hermitian materials can exhibit not only exotic energy band structures but also an anomalous velocity induced by non-Hermitian anomalous Berry connection as predicted by the semiclassical equations of motion for Bloch electrons. However, it is unclear how the modified semiclassical dynamics modifies transport phenomena.Here, we theoretically demonstrate the emergence of anomalous oscillations driven by either an external dc or ac electric field, which arise from non-Hermitian anomalous Berry connection. Moreover, it is a well-known fact that geometric structures of electric wave functions can only affect the Hall conductivity. However, we are surprised to find a non-Hermitian anomalous Berry connection induced anomalous linear longitudinal conductivity independent of the scattering time. We also show the emergence of a second-order nonlinear longitudinal conductivity induced by non-Hermitian anomalous Berry connection, violating a well-known fact of its absence in a Hermitian system with symmetric energy spectra. These anomalous phenomena are illustrated in a pseudo-Hermitian system with large non-Hermitian anomalous Berry connection. Finally, we propose a practical scheme to realize the anomalous oscillations in an optical system.

关 键 词：spectra. BERRY CONDUCTIVITY 

分 类 号：O469[理学—凝聚态物理]