Finite-size-induced non-Hermitian phase transitions in real space  

作　　者：Hongfei Wang Biye Xie Wei Ren 

机构地区：[1]Department of Physics,International Center for Quantum and Molecular Structures,Shanghai University,Shanghai 200444,China [2]School of Science and Engineering,The Chinese University of Hong Kong,Shenzhen 518172,China

出　　处：《Science China(Physics,Mechanics & Astronomy)》2024年第11期105-111,共7页中国科学：物理学、力学、天文学（英文版）

基　　金：supported by the National Natural Science Foundation of China (Grant Nos.12304340,12074241,11929401,and 52130204);the Science and Technology Commission of Shanghai Municipality (Grant Nos.20501130600,21JC1402600,and 21JC1402700);the Shanghai Pujiang Program (Grant No.23PJ1403200);the Key Research Project of Zhejiang Laboratory (Grant No.2021PE0AC02);the startup funding of the Chinese University of Hong Kong,Shenzhen (Grant No.UDF01002563)。

摘　　要：While non-Hermiticity provokes intriguing phenomena without Hermitian counterparts, e.g., the skin effect and the breakdown of bulk-boundary correspondence, attracting extensive attention both in fundamental physics and device engineering, the role of finite sizes therein remains elusive. Here, we propose a class of finite-size-induced non-Hermitian phase transitions, relying upon higher-order topological invariants associated with real-space wave functions. The phase diagrams for general non-Hermitian chiral models are further acquired to demonstrate our topological definition. Such phase transitions are elucidated qualitatively by an effective intercell coupling alteration that depends on finite sizes in respective directions. Besides, we mimic these phenomena by analogizing the circuit Laplacian in finite-size electric circuits with nonreciprocal couplings. The resultant admittance spectra agree with our theoretical predictions. Our findings shed light on the finite-size mechanism of non-Hermitian topological phase transitions and pave the way for applications in switching and sensing.

关 键 词：non-Hermitian phase transitions finite-size effects higher-order topological invariants 

分 类 号：O469[理学—凝聚态物理]