Non-Hermitian topological photonics

Recent years have witnessed a flurry of research activities in topological photonics, predominantly driven by the prospect for topological protection-a property that endows such systems with robustness against local defects, disorder, and perturbations. This field emerged in fermionic environments and primarily evolved within the framework of quantum mechanics which is by nature a Hermitian theory. However, in light of the ubiquitous presence of non-Her miticity in a host of natural and artificial settings, one of the most pressing questions today is how non -Her miticity may affect some of the predominant features of topological arrangements and whether or not novel topological phases may arise in non-conservative and out of equilibrium systems that are open to the environment. Here, we provide a brief overview of recent developments and ongoing efforts in this field and present our perspective on future directions and potential challenges. Special attention will be given to the interplay of topology and non-Hermiticity-an aspect that could open up new frontiers in physical sciences and could lead to promising opportunities in terms of applications in various disciplines of photonics.

Automated summary

Recent years have seen a surge of research in topological photonics, driven by the prospect of topological protection against defects, disorder, and perturbations. This field initially emerged in fermionic systems within the framework of quantum mechanics, but the presence of non-Hermiticity in many natural and artificial settings raises questions about its impact on topological arrangements and the possibility of new topological phases in non-conservative and out of equilibrium systems. This article provides an overview of recent developments and ongoing efforts in this field, highlighting the interplay between topology and non-Hermiticity and its potential for new frontiers and applications in photonics.