Manipulation of edge states in non-Hermitian acoustic Su Schrieffer Heeger chains

A distinctive feature of topology is its unique ability to obtain and control robust interface states. Among other elements, it has been shown that non-Hermiticity alone can trigger topological phase transition in physical systems. In this work, we construct acoustic Su Schrieffer Heeger(SSH) chains using different unit cells where only the non Hermitian components differ due to different distributions of onsite losses. Our study focus on exploring the emergence of edge states at the interfaces between two chains composed of different unit cells. Our findings delineate three distinct types of edge modes. The topological, cavity and Parity-Time edge modes originate from the topological phase of the unit cells, the local parity symmetry at the interface and the existence of a Parity Time symmetric domain wall, respectively. We then compare the robustness of these different edge modes against disorder, confirming the robustness of the topological edge modes. Parity Time edge states demonstrate superior robustness compared to classical cavity modes for low level of disorder. However, beyond a certain threshold, their eigenfrequencies importantly diverge.