Non-Hermitian topological systems with eigenvalues that are always real
The effect of non-Hermiticity in band topology has sparked many discussions on non-Hermitian topological physics. It has long been known that non-Hermitian Hamiltonians can exhibit real energy spectra under the condition of parity-time (PT) symmetry - commonly implemented with balanced loss and gain...
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Format: | Journal Article |
Language: | English |
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2022
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Online Access: | https://hdl.handle.net/10356/156861 |
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author | Long, Yang Xue, Haoran Zhang, Baile |
author2 | School of Physical and Mathematical Sciences |
author_facet | School of Physical and Mathematical Sciences Long, Yang Xue, Haoran Zhang, Baile |
author_sort | Long, Yang |
collection | NTU |
description | The effect of non-Hermiticity in band topology has sparked many discussions on non-Hermitian topological physics. It has long been known that non-Hermitian Hamiltonians can exhibit real energy spectra under the condition of parity-time (PT) symmetry - commonly implemented with balanced loss and gain - but only when non-Hermiticity is relatively weak. Sufficiently strong non-Hermiticity, on the other hand, will destroy the reality of energy spectra, a situation known as spontaneous PT-symmetry breaking. Here, based on nonreciprocal coupling, we show a systematic strategy to construct non-Hermitian topological systems exhibiting bulk and boundary energy spectra that are always real, regardless of weak or strong non-Hermiticity. Such nonreciprocal-coupling-based non-Hermiticity can directly drive a topological phase transition and determine the band topology, as demonstrated in a few non-Hermitian systems from one dimensional to two dimensional. Our work develops a theory that can guarantee the reality of energy spectra for non-Hermitian Hamiltonians, and offers an avenue to explore non-Hermitian topological physics. |
first_indexed | 2024-10-01T05:10:22Z |
format | Journal Article |
id | ntu-10356/156861 |
institution | Nanyang Technological University |
language | English |
last_indexed | 2024-10-01T05:10:22Z |
publishDate | 2022 |
record_format | dspace |
spelling | ntu-10356/1568612023-02-28T20:04:14Z Non-Hermitian topological systems with eigenvalues that are always real Long, Yang Xue, Haoran Zhang, Baile School of Physical and Mathematical Sciences Science::Physics Science::Physics::Atomic physics::Solid state physics Topology Hermitians The effect of non-Hermiticity in band topology has sparked many discussions on non-Hermitian topological physics. It has long been known that non-Hermitian Hamiltonians can exhibit real energy spectra under the condition of parity-time (PT) symmetry - commonly implemented with balanced loss and gain - but only when non-Hermiticity is relatively weak. Sufficiently strong non-Hermiticity, on the other hand, will destroy the reality of energy spectra, a situation known as spontaneous PT-symmetry breaking. Here, based on nonreciprocal coupling, we show a systematic strategy to construct non-Hermitian topological systems exhibiting bulk and boundary energy spectra that are always real, regardless of weak or strong non-Hermiticity. Such nonreciprocal-coupling-based non-Hermiticity can directly drive a topological phase transition and determine the band topology, as demonstrated in a few non-Hermitian systems from one dimensional to two dimensional. Our work develops a theory that can guarantee the reality of energy spectra for non-Hermitian Hamiltonians, and offers an avenue to explore non-Hermitian topological physics. Ministry of Education (MOE) National Research Foundation (NRF) Published version This research is supported by Singapore National Research Fundation Competitive Research Program under Grant No. NRF-CRP23-2019-0007, and Singapore Ministry of Education Academic Research Fund Tier 3 under Grant No. MOE2016-T3-1-006 and Tier 2 under Grant No. MOE2018-T2-1-022 2022-05-04T02:39:57Z 2022-05-04T02:39:57Z 2022 Journal Article Long, Y., Xue, H. & Zhang, B. (2022). Non-Hermitian topological systems with eigenvalues that are always real. Physical Review B, 105(10), L100102-. https://dx.doi.org/10.1103/PhysRevB.105.L100102 2469-9950 https://hdl.handle.net/10356/156861 10.1103/PhysRevB.105.L100102 2-s2.0-85127839129 10 105 L100102 en NRF-CRP23-2019-0007 MOE2016-T3-1-006 MOE2018‐T2‐1‐022 (S) Physical Review B © 2022 American Physical Society. All rights reserved. This paper was published in Physical Review B and is made available with permission of American Physical Society. application/pdf |
spellingShingle | Science::Physics Science::Physics::Atomic physics::Solid state physics Topology Hermitians Long, Yang Xue, Haoran Zhang, Baile Non-Hermitian topological systems with eigenvalues that are always real |
title | Non-Hermitian topological systems with eigenvalues that are always real |
title_full | Non-Hermitian topological systems with eigenvalues that are always real |
title_fullStr | Non-Hermitian topological systems with eigenvalues that are always real |
title_full_unstemmed | Non-Hermitian topological systems with eigenvalues that are always real |
title_short | Non-Hermitian topological systems with eigenvalues that are always real |
title_sort | non hermitian topological systems with eigenvalues that are always real |
topic | Science::Physics Science::Physics::Atomic physics::Solid state physics Topology Hermitians |
url | https://hdl.handle.net/10356/156861 |
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