Non-Hermitian systems exhibit two unique hallmarks:exceptional points(EPs)and non-Hermitian skin effect(NHSE).The EP arises from the interplay of multiple energy levels,marked by degeneracy in eigenvalue spectra,while...Non-Hermitian systems exhibit two unique hallmarks:exceptional points(EPs)and non-Hermitian skin effect(NHSE).The EP arises from the interplay of multiple energy levels,marked by degeneracy in eigenvalue spectra,while the NHSE is associated with the localization feature of eigenfunctions.Due to their different origins and consequences,the interplay between the two hallmarks has drawn considerable interest.Here,we propose the concept of coupled NHSE,i.e.,two non-Hermitian systems with independent NHSE are coupled together.We find that by introducing non-Hermitian losses with special symmetry,multiple pairs of EPs can appear,greatly compressing the eigenvalue spectrum and accelerating the breakdown of the coupled NHSE.In contrast,the attenuation of coupled NHSE is significantly alleviated in systems without EPs.In this sense,the EP can act as a degree of freedom to tune the NHSE and govern the non-Hermitian dynamics.The proposed concept is experimentally realized in photonic lattices with artificial gauge fields,which will bridge these two significant concepts and open avenues for non-Hermitian applications simultaneously associated with them.展开更多
基金supported by National Key Research and Development Program of China(2024YFB4608100)the Young Top-Notch Talent for Ten Thousand Talent Program(X.L.Z.and Z.N.T.)+2 种基金National Natural Science Foundation of China(Grants No.12374350,No.61827826,No.62375103)the Major Science and Technology Projects in Jilin Province(20220301002GX)Innovation Program for Quantum Science and Technology(Grant No.2021ZD0300701).
文摘Non-Hermitian systems exhibit two unique hallmarks:exceptional points(EPs)and non-Hermitian skin effect(NHSE).The EP arises from the interplay of multiple energy levels,marked by degeneracy in eigenvalue spectra,while the NHSE is associated with the localization feature of eigenfunctions.Due to their different origins and consequences,the interplay between the two hallmarks has drawn considerable interest.Here,we propose the concept of coupled NHSE,i.e.,two non-Hermitian systems with independent NHSE are coupled together.We find that by introducing non-Hermitian losses with special symmetry,multiple pairs of EPs can appear,greatly compressing the eigenvalue spectrum and accelerating the breakdown of the coupled NHSE.In contrast,the attenuation of coupled NHSE is significantly alleviated in systems without EPs.In this sense,the EP can act as a degree of freedom to tune the NHSE and govern the non-Hermitian dynamics.The proposed concept is experimentally realized in photonic lattices with artificial gauge fields,which will bridge these two significant concepts and open avenues for non-Hermitian applications simultaneously associated with them.
