Anomalous features of non-Hermitian topological states

Topological states in non-Hermitian systems are known to exhibit some anomalous features. Here, we find two new anomalous features of non-Hermitian topological states. We consider a one dimensional nonreciprocal Hamiltonian and show that topological robustness can be practically lost for a linear combination of topological states in non-Hermitian systems due to the non-Hermitian skin effect. We also consider a two dimensional non-Hermitian Chern insulator and show that chirality of topological states is broken. This implies that topological states are no longer immune to backscattering. (C) 2020 Elsevier Inc. All rights reserved.