Non-Hermitian $C_{NH} = 2$ Chern insulator protected by generalized rotational symmetry

• URL: http://arxiv.org/abs/2111.12573v2
• Date: Fri, 28 Jan 2022 00:17:51 GMT
• Title: Non-Hermitian $C_{NH} = 2$ Chern insulator protected by generalized rotational symmetry
• Authors: Kai Chen and Alexander B. Khanikaev
• Abstract summary: A non-Hermitian system is protected by the generalized rotational symmetry $H+=UHU+$ of the system. Our finding paves the way towards novel non-Hermitian topological systems characterized by large values of topological invariants.
• Score: 85.36456486475119
• License: http://creativecommons.org/licenses/by/4.0/
• Abstract: We propose a non-Hermitian topological system protected by the generalized rotational symmetry which invokes rotation in space and Hermitian conjugation. The system, described by the tight-binding model with nonreciprocal hopping, is found to host two pairs of in-gap edge modes in the gapped topological phase and is characterized by the non-Hermitian (NH) Chern number $C_{NH}=2$. The quantization of the non-Hermitian Chern number is shown to be protected by the generalized rotational symmetry $\^H^{+}=\^U\^H\^U^{+}$ of the system. Our finding paves the way towards novel non-Hermitian topological systems characterized by large values of topological invariants and hosting multiple in-gap edge states, which can be used for topologically resilient multiplexing.

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