Both theoretical and experimental studies of topological phases in non-Hermitian systems
have made a remarkable progress in the last few years of research. In this article, we review …

Topological photonics is a rapidly emerging field of research in which geometrical and
topological ideas are exploited to design and control the behavior of light. Drawing …

In spatially periodic Hermitian systems, such as electronic systems in crystals, the band
structure is described by the band theory in terms of the Bloch wave functions, which …

The bulk-boundary correspondence is among the central issues of non-Hermitian
topological states. We show that a previously overlooked “non-Hermitian skin effect” …

While Hermiticity lies at the heart of quantum mechanics, recent experimental advances in
controlling dissipation have brought about unprecedented flexibility in engineering non …

One of the unique features of non-Hermitian Hamiltonians is the non-Hermitian skin effect,
namely, that the eigenstates are exponentially localized at the boundary of the system. For …

The relation between chiral edge modes and bulk Chern numbers of quantum Hall
insulators is a paradigmatic example of bulk-boundary correspondence. We show that the …

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 …

The topology of non-Hermitian systems is drastically shaped by the non-Hermitian skin
effect, which leads to the generalized bulk-boundary correspondence and non-Bloch band …

Exceptional points are universal level degeneracies induced by non-Hermiticity. Whereas
past decades witnessed their new physics, the unified understanding has yet to be obtained …