PT phase transitions of edge states at PT symmetric interfaces in non-Hermitian topological insulators

We demonstrate that the parity-time (PT) symmetric interfaces formed between non-Hermitian amplifying (“gainy”) and lossy topological crystals exhibit PT phase transitions separating phases of lossless and decaying/amplifying topological edge transport. The spectrum of these interface states exhibit...

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Main Authors: Ni, Xiang, Smirnova, Daria, Poddubny, Alexander, Leykam, Daniel, Chong, Yidong, Khanikaev, Alexander B.
Other Authors: School of Physical and Mathematical Sciences
Format: Article
Language:English
Published: 2019
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Online Access:https://hdl.handle.net/10356/103973
http://hdl.handle.net/10220/47405
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Institution: Nanyang Technological University
Language: English
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spelling sg-ntu-dr.10356-1039732023-02-28T19:43:14Z PT phase transitions of edge states at PT symmetric interfaces in non-Hermitian topological insulators Ni, Xiang Smirnova, Daria Poddubny, Alexander Leykam, Daniel Chong, Yidong Khanikaev, Alexander B. School of Physical and Mathematical Sciences Centre for Disruptive Photonic Technologies (CDPT) DRNTU::Science::Physics Parity-Time (PT) Symmetry Topological Insulators We demonstrate that the parity-time (PT) symmetric interfaces formed between non-Hermitian amplifying (“gainy”) and lossy topological crystals exhibit PT phase transitions separating phases of lossless and decaying/amplifying topological edge transport. The spectrum of these interface states exhibits exceptional points (EPs) separating (i) a PT symmetric real-valued regime with an evenly distributed wave function in both gainy and lossy domains and (ii) a PT broken complex-valued regime, in which edge states asymmetrically localize in one of the domains. Despite its complex-valued character, the edge spectrum remains gapless and connects complex-valued bulk bands through the EPs. We find that the regimes exist when the real edge spectrum is embedded into the bulk continuum without mixing, indicating that the edge states are protected against leakage into the bulk by the PT symmetry. Two exemplary PT symmetric systems, exhibiting valley and Chern topological phases, respectively, are investigated and the connection with the corresponding Hermitian systems is established. Interestingly, despite the complex bulk spectrum of the Chern insulator, the bulk-interface correspondence principle still holds, as long as the topological gap remains open. The proposed systems are experimentally feasible in photonics, which is evidenced by our rigorous full-wave simulations of PT symmetric silicon-based photonic graphene. MOE (Min. of Education, S’pore) Published version 2019-01-07T07:14:18Z 2019-12-06T21:23:45Z 2019-01-07T07:14:18Z 2019-12-06T21:23:45Z 2018 Journal Article Ni, X., Smirnova, D., Poddubny, A., Leykam, D., Chong, Y., & Khanikaev, A. B. (2018). PT phase transitions of edge states at PT symmetric interfaces in non-Hermitian topological insulators. Physical Review B, 98(16), 165129-. doi:10.1103/PhysRevB.98.165129 2469-9950 https://hdl.handle.net/10356/103973 http://hdl.handle.net/10220/47405 10.1103/PhysRevB.98.165129 en Physical Review B © 2018 American Physical Society (APS). All rights reserved. This paper was published in Physical Review B and is made available with permission of American Physical Society (APS). 13 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 DRNTU::Science::Physics
Parity-Time (PT) Symmetry
Topological Insulators
spellingShingle DRNTU::Science::Physics
Parity-Time (PT) Symmetry
Topological Insulators
Ni, Xiang
Smirnova, Daria
Poddubny, Alexander
Leykam, Daniel
Chong, Yidong
Khanikaev, Alexander B.
PT phase transitions of edge states at PT symmetric interfaces in non-Hermitian topological insulators
description We demonstrate that the parity-time (PT) symmetric interfaces formed between non-Hermitian amplifying (“gainy”) and lossy topological crystals exhibit PT phase transitions separating phases of lossless and decaying/amplifying topological edge transport. The spectrum of these interface states exhibits exceptional points (EPs) separating (i) a PT symmetric real-valued regime with an evenly distributed wave function in both gainy and lossy domains and (ii) a PT broken complex-valued regime, in which edge states asymmetrically localize in one of the domains. Despite its complex-valued character, the edge spectrum remains gapless and connects complex-valued bulk bands through the EPs. We find that the regimes exist when the real edge spectrum is embedded into the bulk continuum without mixing, indicating that the edge states are protected against leakage into the bulk by the PT symmetry. Two exemplary PT symmetric systems, exhibiting valley and Chern topological phases, respectively, are investigated and the connection with the corresponding Hermitian systems is established. Interestingly, despite the complex bulk spectrum of the Chern insulator, the bulk-interface correspondence principle still holds, as long as the topological gap remains open. The proposed systems are experimentally feasible in photonics, which is evidenced by our rigorous full-wave simulations of PT symmetric silicon-based photonic graphene.
author2 School of Physical and Mathematical Sciences
author_facet School of Physical and Mathematical Sciences
Ni, Xiang
Smirnova, Daria
Poddubny, Alexander
Leykam, Daniel
Chong, Yidong
Khanikaev, Alexander B.
format Article
author Ni, Xiang
Smirnova, Daria
Poddubny, Alexander
Leykam, Daniel
Chong, Yidong
Khanikaev, Alexander B.
author_sort Ni, Xiang
title PT phase transitions of edge states at PT symmetric interfaces in non-Hermitian topological insulators
title_short PT phase transitions of edge states at PT symmetric interfaces in non-Hermitian topological insulators
title_full PT phase transitions of edge states at PT symmetric interfaces in non-Hermitian topological insulators
title_fullStr PT phase transitions of edge states at PT symmetric interfaces in non-Hermitian topological insulators
title_full_unstemmed PT phase transitions of edge states at PT symmetric interfaces in non-Hermitian topological insulators
title_sort pt phase transitions of edge states at pt symmetric interfaces in non-hermitian topological insulators
publishDate 2019
url https://hdl.handle.net/10356/103973
http://hdl.handle.net/10220/47405
_version_ 1759856149107048448