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arXiv · 2004.01886

Real spectra in non-Hermitian topological insulators

Kohei Kawabata·Masatoshi Sato
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Abstract

Spectra of bulk or edges in topological insulators are often made complex by non-Hermiticity. Here, we show that symmetry protection enables entirely real spectra for both bulk and edges even in non-Hermitian topological insulators. In particular, we demonstrate entirely real spectra without non-Hermitian skin effects due to a combination of pseudo-Hermiticity and Kramers degeneracy. This protection relies on nonspatial fundamental symmetry and has stability against disorder. As an illustrative example, we investigate a non-Hermitian extension of the Bernevig-Hughes-Zhang model. The helical edge states exhibit oscillatory dynamics due to their nonorthogonality as a unique non-Hermitian feature.

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Kohei Kawabata, Masatoshi Sato. 2020-04-04. Real spectra in non-Hermitian topological insulators. https://doi.org/10.1103/physrevresearch.2.033391

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