Experimental realization of non-Abelian permutations in a three-state non-Hermitian system  

作　　者：Weiyuan Tang Kun Ding Guancong Ma 

机构地区：[1]Department of Physics,Hong Kong Baptist University,Hong Kong,China [2]Department of Physics,State Key Laboratory of Surface Physics,and Key Laboratory of Micro and Nano Photonic Structures(Ministry of Education),Fudan University,Shanghai 200438,China

出　　处：《National Science Review》2022年第11期74-81,共8页国家科学评论（英文版）

基　　金：supported by the National Natural Science Foundation of China (11922416,11802256 and 12174072);the Hong Kong Research Grants Council (12302420, 12300419, 22302718 and C6013-18 G);the Hong Kong Baptist University(RC-SGT2/18-19/SCI/006)

摘　　要：Eigenstates of a non-Hermitian system exist on complex Riemannian manifolds,with multiple sheets connecting at branch cuts and exceptional points(EPs).These eigenstates can evolve across different sheets—a process that naturally corresponds to state permutation.Here,we report the first experimental realization of non-Abelian permutations in a three-state non-Hermitian system.Our approach relies on the stroboscopic encircling of two different exceptional arcs(EAs),which are smooth trajectories of order-2EPs appearing from the coalescence of two adjacent states.The non-Abelian characteristics are confirmed by encircling the EAs in opposite sequences.A total of five non-trivial permutations are experimentally realized,which together comprise a non-Abelian group.Our approach provides a reliable way of investigating non-Abelian state permutations and the related exotic winding effects in non-Hermitian systems.

关 键 词：non-Abelian permutation non-Hermitian physics topological physics acoustics 

分 类 号：O469[理学—凝聚态物理]