Floquet topological acoustic resonators and acoustic Thouless pumping.

Constructing the topological states can serve as a promising approach for robust acoustic wave transports and manipulations. Here, the authors develop a scheme to realize acoustic topological states and adiabatic Thouless pumping in acoustic Floquet resonator systems. The directional acoustic wave can be robustly manipulated and pumped adiabatically from one side to the opposite side due to the non-trivial topological nature. The physical mechanism behind these phenomena can be understood by effective one-dimensional Aubry-André-Harper Hamiltonian, with an additional synthetic dimension originating from Floquet spatially periodic modulation. This Aubry-André-Harper acoustic resonator system can be regarded as a projection from a two-dimensional topological Hofstadter model for the integer quantum Hall effect. The authors' scheme provides a promising method for synthesizing acoustic topological states for efficient acoustic wave manipulations. Introducing the topological mechanism to the control wave will become an alternative method besides the conventional effective acoustic parameter methods.