The Hopf insulator is a representative class of three-dimensional topological insulators
beyond the standard topological classification methods based on K theory. In this Letter, we …

The Hopf insulator is a three-dimensional topological insulator outside the standard
classification of topological insulators. Here we consider two types of non-Hermitian Hopf …

Non-Abelian topological charges have recently been proposed to characterize the
noncommutative topological properties in multiple-band-gap systems. In this work, we …

We study PT symmetry protected topological phase in non-Hermitian 1D and 2D systems.
We show that topological phase exist in non-Hermitian PT symmetric systems for both …

We study a non-Hermitian non-Abelian topological insulator preserving PT symmetry, where
the non-Hermitian term represents nonreciprocal hoppings. As it increases, a spontaneous …

Non-Hermiticity gives rise to distinctive topological phenomena absent in Hermitian systems.
However, connection between such intrinsic non-Hermitian topology and Hermitian topology …

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 …

A d-dimensional second-order topological insulator (SOTI) can host topologically protected
(d-2)-dimensional gapless boundary modes. Here, we show that a 2D non-Hermitian SOTI …

We propose a two-dimensional non-Hermitian Chern insulator with inversion symmetry,
which is anisotropic and has staggered gain and loss in both x and y directions. In this …

Point-gap topological phases of non-Hermitian systems exhibit exotic boundary states that
have no counterparts in Hermitian systems. Here, we develop classification of second-order …