Non-Hermitian skin effect and delocalized edge states in photonic crystals with anomalous parity-time symmetry

TL;DR

This paper demonstrates the non-Hermitian skin effect and delocalized edge states in photonic crystals with anomalous parity-time symmetry, revealing their dependence on frequency and chirality, and opening new avenues in non-Hermitian photonics.

Contribution

It analytically reveals the non-Hermitian skin effect and delocalized edge states in Maxwell's equations for chiral photonic crystals with anomalous parity-time symmetry, a novel insight in realistic photonic systems.

Findings

Edge state penetration depth is inversely proportional to frequency.

Non-Hermitian skin effect causes eigenstate localization in photonic lattices.

Delocalized edge modes can occur in non-Hermitian photonic systems.

Abstract

Non-Hermitian skin effect denotes the exponential localization of a large number of eigen-states in a non-Hermitian lattice under open boundary conditions. Such a non-Hermiticity-induced skin effect can offset the penetration depth of in-gap edge states, leading to counterintuitive delocalized edge modes, which have not been studied in a realistic photonic system such as photonic crystals. Here, we analytically reveal the non-Hermitian skin effect and the delocalized edge states in Maxwell's equations for non-Hermitian chiral photonic crystals with anomalous parity-time symmetry. Remarkably, we rigorously prove that the penetration depth of the edge states is inversely proportional to the frequency and the real part of the chirality. Our findings pave a way towards exploring novel non-Hermitian phenomena and applications in continuous Maxwell's equations.