Bulk-edge coulping induced by a moving impurity

Abstract

More physics at the boundaries of a topological lattice remains to be explored for future applications of topological edge states. This work investigates the stability of topological edge states in the presence of a moving impurity. By modeling the impurity as a moving Gaussian on-site potential at the boundary of a two-dimensional (2D) lattice, we show that a moving impurity may cause significant modifications to edge transport, a feature markedly different from the expected robustness of edge transport against a static impurity. We further identify an interesting mechanism to explain the bulk-edge coupling using a co-moving frame, where the density of the bulk states and the degeneracy between the edge states and the bulk become key elements. The physical insights developed in this work are validated across multiple systems, including Chern insulators, quantum spin Hall insulators, and Floquet Chern insulators. Results presented in this work are complementary to our current understanding of the robustness of topological edge transport.

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