Simultaneous Observation of Topological Edge State and Exceptional Point in an Open and Non-Hermitian System

This paper reports on the experimental observation of topologically protected edge state and exceptional point in an open and Non-Hermitian system. While the theoretical underpinning is generic to wave physics, the simulations and experiments are performed for an acoustic system whose structure has non-trivial topological properties that can be characterized by the Chern number provided that a synthetic dimension is introduced. Unidirectional reectionless propagation, a hallmark of exceptional point, is unambiguously observed in both simulations and experiments.