By introducing a lattice translation of the unit cell of a phononic crystal, a general recipe to invert the acoustic Zak phase—i.e. the one-dimensional geometric phase at each phononic band—is provided and verified by surface impedance measurement. Multiband acoustic interface states are thus generated and may help the design of future acoustic waveguides. The propagation properties of these topological interface states are experimentally obtained and we believe that the methods to measure surface impedance and local sound pressure distributions inside phononic crystals developed here can further help experimental studies in acoustic metamaterials.

中文翻译：

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由二维声子晶体构成的多频带声波导

通过引入声子晶体的晶胞的晶格平移，提供了一种通用的配方，用于反转声Zak相（即每个声子带上的一维几何相），并通过表面阻抗测量进行了验证。因此，产生了多频带声界面状态，并且可以帮助设计未来的声波导。这些拓扑界面态的传播特性是通过实验获得的，我们相信此处开发的用于测量声子晶体内部表面阻抗和局部声压分布的方法可以进一步帮助声学超材料的实验研究。