Non-Hermitian route to higher-order topology in an acoustic crystal
Topological phases of matter are classified based on their Hermitian Hamiltonians, whose real-valued dispersions together with orthogonal eigenstates form nontrivial topology. In the recently discovered higher-order topological insulators (TIs), the bulk topology can even exhibit hierarchical featur...
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sg-ntu-dr.10356-1548092023-02-28T20:02:33Z Non-Hermitian route to higher-order topology in an acoustic crystal Gao, He Xue, Haoran Gu, Zhongming Liu, Tuo Zhu, Jie Zhang, Baile School of Physical and Mathematical Sciences Centre for Disruptive Photonic Technologies (CDPT) Science::Physics Topological Insulators Non-Hermitian Physics Topological phases of matter are classified based on their Hermitian Hamiltonians, whose real-valued dispersions together with orthogonal eigenstates form nontrivial topology. In the recently discovered higher-order topological insulators (TIs), the bulk topology can even exhibit hierarchical features, leading to topological corner states, as demonstrated in many photonic and acoustic artificial materials. Naturally, the intrinsic loss in these artificial materials has been omitted in the topology definition, due to its non-Hermitian nature; in practice, the presence of loss is generally considered harmful to the topological corner states. Here, we report the experimental realization of a higher-order TI in an acoustic crystal, whose nontrivial topology is induced by deliberately introduced losses. With local acoustic measurements, we identify a topological bulk bandgap that is populated with gapped edge states and in-gap corner states, as the hallmark signatures of hierarchical higher-order topology. Our work establishes the non-Hermitian route to higher-order topology, and paves the way to exploring various exotic non-Hermiticity-induced topological phases. Ministry of Education (MOE) Published version This research is supported by the General Research Fund scheme of Research Grants Council of Hong Kong under Grant No. 15205219 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(S). 2022-01-10T07:24:26Z 2022-01-10T07:24:26Z 2021 Journal Article Gao, H., Xue, H., Gu, Z., Liu, T., Zhu, J. & Zhang, B. (2021). Non-Hermitian route to higher-order topology in an acoustic crystal. Nature Communications, 12(1), 1888-. https://dx.doi.org/10.1038/s41467-021-22223-y 2041-1723 https://hdl.handle.net/10356/154809 10.1038/s41467-021-22223-y 33767167 2-s2.0-85103185598 1 12 1888 en MOE2016-T3-1-006 MOE2018-T2-1-022(S) Nature Communications 10.21979/N9/RPUOVM © 2021 The Author(s). 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/. application/pdf |
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Science::Physics Topological Insulators Non-Hermitian Physics Gao, He Xue, Haoran Gu, Zhongming Liu, Tuo Zhu, Jie Zhang, Baile Non-Hermitian route to higher-order topology in an acoustic crystal |
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Topological phases of matter are classified based on their Hermitian Hamiltonians, whose real-valued dispersions together with orthogonal eigenstates form nontrivial topology. In the recently discovered higher-order topological insulators (TIs), the bulk topology can even exhibit hierarchical features, leading to topological corner states, as demonstrated in many photonic and acoustic artificial materials. Naturally, the intrinsic loss in these artificial materials has been omitted in the topology definition, due to its non-Hermitian nature; in practice, the presence of loss is generally considered harmful to the topological corner states. Here, we report the experimental realization of a higher-order TI in an acoustic crystal, whose nontrivial topology is induced by deliberately introduced losses. With local acoustic measurements, we identify a topological bulk bandgap that is populated with gapped edge states and in-gap corner states, as the hallmark signatures of hierarchical higher-order topology. Our work establishes the non-Hermitian route to higher-order topology, and paves the way to exploring various exotic non-Hermiticity-induced topological phases. |
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School of Physical and Mathematical Sciences |
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School of Physical and Mathematical Sciences Gao, He Xue, Haoran Gu, Zhongming Liu, Tuo Zhu, Jie Zhang, Baile |
format |
Article |
author |
Gao, He Xue, Haoran Gu, Zhongming Liu, Tuo Zhu, Jie Zhang, Baile |
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Gao, He |
title |
Non-Hermitian route to higher-order topology in an acoustic crystal |
title_short |
Non-Hermitian route to higher-order topology in an acoustic crystal |
title_full |
Non-Hermitian route to higher-order topology in an acoustic crystal |
title_fullStr |
Non-Hermitian route to higher-order topology in an acoustic crystal |
title_full_unstemmed |
Non-Hermitian route to higher-order topology in an acoustic crystal |
title_sort |
non-hermitian route to higher-order topology in an acoustic crystal |
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2022 |
url |
https://hdl.handle.net/10356/154809 |
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1759857465791348736 |