Hermitian chiral boundary states in non-Hermitian topological insulators

Eigenenergies of a non-Hermitian system without parity-time symmetry are complex in general. Here, we show that the chiral boundary states higher-dimensional topological insulators can be Hermitian with real eigenenergies under certain conditions. Our approach allows one to construct edge and hinge from two-dimensional Chern three-dimensional second-order insulators, respectively. Such channels have perfect transmission coefficients (quantized values) robust against disorders. Furthermore, insulator undergo Anderson transition topologically trivial metal or quantized at finite