Edge Modes, Degeneracies, and Topological Numbers in Non-Hermitian Systems

We analyze chiral topological edge modes in a non-Hermitian variant of the 2D Dirac equation. Such modes appear at interfaces between media with different “masses” and/or signs of the “non-Hermitian charge.” The existence of these edge modes is intimately related to exceptional points of the bulk Ha...

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Main Authors: Chong, Yi Dong, Nori, Franco, Leykam, Daniel, Bliokh, Konstantin Y., Huang, Chunli
Other Authors: School of Physical and Mathematical Sciences
Format: Article
Language:English
Published: 2017
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Online Access:https://hdl.handle.net/10356/83306
http://hdl.handle.net/10220/42547
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Institution: Nanyang Technological University
Language: English
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spelling sg-ntu-dr.10356-833062023-02-28T19:32:32Z Edge Modes, Degeneracies, and Topological Numbers in Non-Hermitian Systems Chong, Yi Dong Nori, Franco Leykam, Daniel Bliokh, Konstantin Y. Huang, Chunli School of Physical and Mathematical Sciences Centre for Disruptive Photonic Technologies (CDPT) Honeycomb structures Linear equations We analyze chiral topological edge modes in a non-Hermitian variant of the 2D Dirac equation. Such modes appear at interfaces between media with different “masses” and/or signs of the “non-Hermitian charge.” The existence of these edge modes is intimately related to exceptional points of the bulk Hamiltonians, i.e., degeneracies in the bulk spectra of the media. We find that the topological edge modes can be divided into three families (“Hermitian-like,” “non-Hermitian,” and “mixed”); these are characterized by two winding numbers, describing two distinct kinds of half-integer charges carried by the exceptional points. We show that all the above types of topological edge modes can be realized in honeycomb lattices of ring resonators with asymmetric or gain-loss couplings. NRF (Natl Research Foundation, S’pore) MOE (Min. of Education, S’pore) Published version 2017-06-01T03:51:25Z 2019-12-06T15:19:39Z 2017-06-01T03:51:25Z 2019-12-06T15:19:39Z 2017 Journal Article Leykam, D., Bliokh, K. Y., Huang, C., Chong, Y. D., & Nori, F. (2017). Edge Modes, Degeneracies, and Topological Numbers in Non-Hermitian Systems. Physical Review Letters, 118(4). 0031-9007 https://hdl.handle.net/10356/83306 http://hdl.handle.net/10220/42547 10.1103/PhysRevLett.118.040401 en Physical Review Letters © 2017 American Physical Society (APS). This paper was published in Physical Review Letters and is made available as an electronic reprint (preprint) with permission of American Physical Society (APS). The published version is available at: [http://dx.doi.org/10.1103/PhysRevLett.118.040401]. One print or electronic copy may be made for personal use only. Systematic or multiple reproduction, distribution to multiple locations via electronic or other means, duplication of any material in this paper for a fee or for commercial purposes, or modification of the content of the paper is prohibited and is subject to penalties under law. 6 p. application/pdf
institution Nanyang Technological University
building NTU Library
continent Asia
country Singapore
Singapore
content_provider NTU Library
collection DR-NTU
language English
topic Honeycomb structures
Linear equations
spellingShingle Honeycomb structures
Linear equations
Chong, Yi Dong
Nori, Franco
Leykam, Daniel
Bliokh, Konstantin Y.
Huang, Chunli
Edge Modes, Degeneracies, and Topological Numbers in Non-Hermitian Systems
description We analyze chiral topological edge modes in a non-Hermitian variant of the 2D Dirac equation. Such modes appear at interfaces between media with different “masses” and/or signs of the “non-Hermitian charge.” The existence of these edge modes is intimately related to exceptional points of the bulk Hamiltonians, i.e., degeneracies in the bulk spectra of the media. We find that the topological edge modes can be divided into three families (“Hermitian-like,” “non-Hermitian,” and “mixed”); these are characterized by two winding numbers, describing two distinct kinds of half-integer charges carried by the exceptional points. We show that all the above types of topological edge modes can be realized in honeycomb lattices of ring resonators with asymmetric or gain-loss couplings.
author2 School of Physical and Mathematical Sciences
author_facet School of Physical and Mathematical Sciences
Chong, Yi Dong
Nori, Franco
Leykam, Daniel
Bliokh, Konstantin Y.
Huang, Chunli
format Article
author Chong, Yi Dong
Nori, Franco
Leykam, Daniel
Bliokh, Konstantin Y.
Huang, Chunli
author_sort Chong, Yi Dong
title Edge Modes, Degeneracies, and Topological Numbers in Non-Hermitian Systems
title_short Edge Modes, Degeneracies, and Topological Numbers in Non-Hermitian Systems
title_full Edge Modes, Degeneracies, and Topological Numbers in Non-Hermitian Systems
title_fullStr Edge Modes, Degeneracies, and Topological Numbers in Non-Hermitian Systems
title_full_unstemmed Edge Modes, Degeneracies, and Topological Numbers in Non-Hermitian Systems
title_sort edge modes, degeneracies, and topological numbers in non-hermitian systems
publishDate 2017
url https://hdl.handle.net/10356/83306
http://hdl.handle.net/10220/42547
_version_ 1759853043970473984