Topologically protected edge transport of sound in coupled cavities of a modified honeycomb lattice.

In this work, we investigate comprehensively the unidirectional transport of sound in coupled cavities of a modified honeycomb lattice. The results clearly show that a pair of topological states carrying opposite pseudospins can be constructed at the edge of truncated lattices of non-trivial band gaps, which is different from previous schemes where topological states with opposite pseudospins were constructed at the interface of modified honeycomb lattices of trivial and non-trivial band gaps. Our work paves the way to exploring unidirectional edge transport of sound with topological protection in closed systems that are beneficial in large-scale device integration and low-loss operation.