Exceptional points and chiral mode conversion in non-Hermitian elastic media

IF 6 2区工程技术 Q2 MATERIALS SCIENCE, MULTIDISCIPLINARY

Journal of The Mechanics and Physics of Solids Pub Date : 2025-10-01 DOI:10.1016/j.jmps.2025.106385

Youdong Duan , Linlin Geng , Guoliang Huang , Xiaoming Zhou

{"title":"Exceptional points and chiral mode conversion in non-Hermitian elastic media","authors":"Youdong Duan , Linlin Geng , Guoliang Huang , Xiaoming Zhou","doi":"10.1016/j.jmps.2025.106385","DOIUrl":null,"url":null,"abstract":"<div><div>Non-Hermitian behaviors for elastic waves, including the parity-time (PT) symmetric and anti-PT symmetric exceptional points (EPs) as well as chiral mode conversion via the dynamic encircling of them, are realized in a unified model based on anisotropic elastic media with complex modulus. Based on the tight-binding approximation of elastodynamic equations, the coupling interaction between elastic wave modes is described by the non-Hermitian Hamiltonian, which is used to derive the existence condition of PT-symmetric and anti-PT-symmetric EPs in different parameter systems. Eigenmode evolution of elastic waves in the process of dynamic encircling of EPs is studied in the spatially modulated model consisting of the multilayered anisotropic media. Chiral mode conversion for elastic waves as dominated by the encircling direction is disclosed by the developed model. The dynamical encircling of a PT-symmetric EP can lead to chiral mode conversion for the symmetric phase, while encircling an anti-PT-symmetric EP results in chiral mode switching for the broken phase. Dynamic evolution along regular and irregular paths are analyzed to demonstrate the topological robustness of chiral mode conversion.</div></div>","PeriodicalId":17331,"journal":{"name":"Journal of The Mechanics and Physics of Solids","volume":"206 ","pages":"Article 106385"},"PeriodicalIF":6.0000,"publicationDate":"2025-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Journal of The Mechanics and Physics of Solids","FirstCategoryId":"5","ListUrlMain":"https://www.sciencedirect.com/science/article/pii/S002250962500359X","RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q2","JCRName":"MATERIALS SCIENCE, MULTIDISCIPLINARY","Score":null,"Total":0}

引用次数: 0

Abstract

Non-Hermitian behaviors for elastic waves, including the parity-time (PT) symmetric and anti-PT symmetric exceptional points (EPs) as well as chiral mode conversion via the dynamic encircling of them, are realized in a unified model based on anisotropic elastic media with complex modulus. Based on the tight-binding approximation of elastodynamic equations, the coupling interaction between elastic wave modes is described by the non-Hermitian Hamiltonian, which is used to derive the existence condition of PT-symmetric and anti-PT-symmetric EPs in different parameter systems. Eigenmode evolution of elastic waves in the process of dynamic encircling of EPs is studied in the spatially modulated model consisting of the multilayered anisotropic media. Chiral mode conversion for elastic waves as dominated by the encircling direction is disclosed by the developed model. The dynamical encircling of a PT-symmetric EP can lead to chiral mode conversion for the symmetric phase, while encircling an anti-PT-symmetric EP results in chiral mode switching for the broken phase. Dynamic evolution along regular and irregular paths are analyzed to demonstrate the topological robustness of chiral mode conversion.

查看原文本刊更多论文

非厄米弹性介质中的异常点和手性模式转换

在基于复模各向异性弹性介质的统一模型中，实现了弹性波的非厄米行为，包括奇偶时对称（PT）和反PT对称异常点（EPs），以及通过它们的动态环绕实现的手性模式转换。基于弹性动力学方程的紧结合近似，用非厄米哈密顿量描述了弹性波模之间的耦合相互作用，推导了不同参数系统中pt对称和反pt对称EPs的存在条件。在由多层各向异性介质组成的空间调制模型中，研究了弹性波在EPs动态环绕过程中的特征模态演化。所建立的模型揭示了受环向支配的弹性波的手性模式转换。pt对称电位的动态环可以导致对称相的手性模式转换，而反pt对称电位的动态环可以导致破碎相的手性模式切换。分析了沿规则路径和不规则路径的动态演化，证明了手性模式转换的拓扑鲁棒性。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

求助全文

约1分钟内获得全文求助全文

来源期刊

Journal of The Mechanics and Physics of Solids 物理-材料科学：综合

CiteScore

9.80

自引率

9.40%

发文量

276

审稿时长

52 days

期刊介绍： The aim of Journal of The Mechanics and Physics of Solids is to publish research of the highest quality and of lasting significance on the mechanics of solids. The scope is broad, from fundamental concepts in mechanics to the analysis of novel phenomena and applications. Solids are interpreted broadly to include both hard and soft materials as well as natural and synthetic structures. The approach can be theoretical, experimental or computational.This research activity sits within engineering science and the allied areas of applied mathematics, materials science, bio-mechanics, applied physics, and geophysics. The Journal was founded in 1952 by Rodney Hill, who was its Editor-in-Chief until 1968. The topics of interest to the Journal evolve with developments in the subject but its basic ethos remains the same: to publish research of the highest quality relating to the mechanics of solids. Thus, emphasis is placed on the development of fundamental concepts of mechanics and novel applications of these concepts based on theoretical, experimental or computational approaches, drawing upon the various branches of engineering science and the allied areas within applied mathematics, materials science, structural engineering, applied physics, and geophysics. The main purpose of the Journal is to foster scientific understanding of the processes of deformation and mechanical failure of all solid materials, both technological and natural, and the connections between these processes and their underlying physical mechanisms. In this sense, the content of the Journal should reflect the current state of the discipline in analysis, experimental observation, and numerical simulation. In the interest of achieving this goal, authors are encouraged to consider the significance of their contributions for the field of mechanics and the implications of their results, in addition to describing the details of their work.