Real spectra in non-Hermitian topological insulators
Kohei Kawabata, Masatoshi Sato
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 the 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.
Topics & Concepts
Topological insulatorSpectral linePhysicsSymmetry (geometry)Topology (electrical circuits)Enhanced Data Rates for GSM EvolutionCondensed matter physicsTheoretical physicsStability (learning theory)Spectrum (functional analysis)Topological orderMirror symmetryLine (geometry)Quantum mechanicsTopological defectExtension (predicate logic)Symmetry protected topological orderQuantum Mechanics and Non-Hermitian PhysicsTopological Materials and PhenomenaQuantum, superfluid, helium dynamics