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Exceptional non-Hermitian topological edge mode and its application to active matter
Topological materials exhibit edge-localized scattering-free modes protected by their nontrivial bulk topology through the bulk-edge correspondence in Hermitian systems. While topological phenomena have recently been much investigated in non-Hermitian systems with dissipations and injections, the fu...
Autores principales: | , , |
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Formato: | Online Artículo Texto |
Lenguaje: | English |
Publicado: |
Nature Publishing Group UK
2020
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Materias: | |
Acceso en línea: | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7665040/ https://www.ncbi.nlm.nih.gov/pubmed/33184296 http://dx.doi.org/10.1038/s41467-020-19488-0 |
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author | Sone, Kazuki Ashida, Yuto Sagawa, Takahiro |
author_facet | Sone, Kazuki Ashida, Yuto Sagawa, Takahiro |
author_sort | Sone, Kazuki |
collection | PubMed |
description | Topological materials exhibit edge-localized scattering-free modes protected by their nontrivial bulk topology through the bulk-edge correspondence in Hermitian systems. While topological phenomena have recently been much investigated in non-Hermitian systems with dissipations and injections, the fundamental principle of their edge modes has not fully been established. Here, we reveal that, in non-Hermitian systems, robust gapless edge modes can ubiquitously appear owing to a mechanism that is distinct from bulk topology, thus indicating the breakdown of the bulk-edge correspondence. The robustness of these edge modes originates from yet another topological structure accompanying the branchpoint singularity around an exceptional point, at which eigenvectors coalesce and the Hamiltonian becomes nondiagonalizable. Their characteristic complex eigenenergy spectra are applicable to realize lasing wave packets that propagate along the edge of the sample. We numerically confirm the emergence and the robustness of the proposed edge modes in the prototypical lattice models. Furthermore, we show that these edge modes appear in a model of chiral active matter based on the hydrodynamic description, demonstrating that active matter can exhibit an inherently non-Hermitian topological feature. The proposed general mechanism would serve as an alternative designing principle to realize scattering-free edge current in non-Hermitian devices, going beyond the existing frameworks of non-Hermitian topological phases. |
format | Online Article Text |
id | pubmed-7665040 |
institution | National Center for Biotechnology Information |
language | English |
publishDate | 2020 |
publisher | Nature Publishing Group UK |
record_format | MEDLINE/PubMed |
spelling | pubmed-76650402020-11-17 Exceptional non-Hermitian topological edge mode and its application to active matter Sone, Kazuki Ashida, Yuto Sagawa, Takahiro Nat Commun Article Topological materials exhibit edge-localized scattering-free modes protected by their nontrivial bulk topology through the bulk-edge correspondence in Hermitian systems. While topological phenomena have recently been much investigated in non-Hermitian systems with dissipations and injections, the fundamental principle of their edge modes has not fully been established. Here, we reveal that, in non-Hermitian systems, robust gapless edge modes can ubiquitously appear owing to a mechanism that is distinct from bulk topology, thus indicating the breakdown of the bulk-edge correspondence. The robustness of these edge modes originates from yet another topological structure accompanying the branchpoint singularity around an exceptional point, at which eigenvectors coalesce and the Hamiltonian becomes nondiagonalizable. Their characteristic complex eigenenergy spectra are applicable to realize lasing wave packets that propagate along the edge of the sample. We numerically confirm the emergence and the robustness of the proposed edge modes in the prototypical lattice models. Furthermore, we show that these edge modes appear in a model of chiral active matter based on the hydrodynamic description, demonstrating that active matter can exhibit an inherently non-Hermitian topological feature. The proposed general mechanism would serve as an alternative designing principle to realize scattering-free edge current in non-Hermitian devices, going beyond the existing frameworks of non-Hermitian topological phases. Nature Publishing Group UK 2020-11-12 /pmc/articles/PMC7665040/ /pubmed/33184296 http://dx.doi.org/10.1038/s41467-020-19488-0 Text en © The Author(s) 2020 Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The images or other third party material in this article are included in the article’s Creative Commons license, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons license and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this license, visit http://creativecommons.org/licenses/by/4.0/. |
spellingShingle | Article Sone, Kazuki Ashida, Yuto Sagawa, Takahiro Exceptional non-Hermitian topological edge mode and its application to active matter |
title | Exceptional non-Hermitian topological edge mode and its application to active matter |
title_full | Exceptional non-Hermitian topological edge mode and its application to active matter |
title_fullStr | Exceptional non-Hermitian topological edge mode and its application to active matter |
title_full_unstemmed | Exceptional non-Hermitian topological edge mode and its application to active matter |
title_short | Exceptional non-Hermitian topological edge mode and its application to active matter |
title_sort | exceptional non-hermitian topological edge mode and its application to active matter |
topic | Article |
url | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7665040/ https://www.ncbi.nlm.nih.gov/pubmed/33184296 http://dx.doi.org/10.1038/s41467-020-19488-0 |
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