Pseudo-Hermitian Topology of Multiband Non-Hermitian Systems

Fuente: arXiv
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Main Authors: Ryu, Jung-Wan, Han, Jae-Ho, Yi, Chang-Hwan, Park, Hee Chul, Park, Moon Jip
Format: Preprint
Published: 2024
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author Ryu, Jung-Wan
Han, Jae-Ho
Yi, Chang-Hwan
Park, Hee Chul
Park, Moon Jip
author_facet Ryu, Jung-Wan
Han, Jae-Ho
Yi, Chang-Hwan
Park, Hee Chul
Park, Moon Jip
contents The complex eigenenergies and non-orthogonal eigenstates of non-Hermitian systems exhibit unique topological phenomena that cannot appear in Hermitian systems. Representative examples are the non-Hermitian skin effect and exceptional points. In a two-dimensional parameter space, topological classifications of non-separable bands in multiband non-Hermitian systems can be established by invoking a permutation group, where the product of the permutation represents state exchange due to exceptional points in the space. We unveil in this work the role of pseudo-Hermitian lines in non-Hermitian topology for multiple bands. In particular, the non-separability of non-Hermitian multibands can be topologically non-trivial without exceptional points in two-dimensional space. As a physical illustration of the role of pseudo-Hermitian lines, we examine a multiband structure of a photonic crystal system with lossy materials. Our work builds on the fundamental and comprehensive understanding of non-Hermitian multiband systems and also offers versatile applications and realizations of non-Hermitian systems without the need to consider exceptional points.
format Preprint
id arxiv_https___arxiv_org_abs_2405_17749
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Pseudo-Hermitian Topology of Multiband Non-Hermitian Systems
Ryu, Jung-Wan
Han, Jae-Ho
Yi, Chang-Hwan
Park, Hee Chul
Park, Moon Jip
Quantum Physics
Mesoscale and Nanoscale Physics
The complex eigenenergies and non-orthogonal eigenstates of non-Hermitian systems exhibit unique topological phenomena that cannot appear in Hermitian systems. Representative examples are the non-Hermitian skin effect and exceptional points. In a two-dimensional parameter space, topological classifications of non-separable bands in multiband non-Hermitian systems can be established by invoking a permutation group, where the product of the permutation represents state exchange due to exceptional points in the space. We unveil in this work the role of pseudo-Hermitian lines in non-Hermitian topology for multiple bands. In particular, the non-separability of non-Hermitian multibands can be topologically non-trivial without exceptional points in two-dimensional space. As a physical illustration of the role of pseudo-Hermitian lines, we examine a multiband structure of a photonic crystal system with lossy materials. Our work builds on the fundamental and comprehensive understanding of non-Hermitian multiband systems and also offers versatile applications and realizations of non-Hermitian systems without the need to consider exceptional points.
title Pseudo-Hermitian Topology of Multiband Non-Hermitian Systems
topic Quantum Physics
Mesoscale and Nanoscale Physics
url https://arxiv.org/abs/2405.17749