Experimental observation of the topological interface state in a one-dimensional waterborne acoustic waveguide

Topological insulators that exhibit localized states at the edges or interference regions have been extensively investigated. Among these, waterborne acoustic topological interface states have significant potential in applications such as particle manipulation. However, the large impedance of water can no longer be ignored and sets difficulty in the construction of the waveguide in observing the topological states. In this paper, we propose an effective strategy to circumvent this issue and achieve the direct observation of the topological interface state in a waterborne acoustic waveguide as well as the associated nonzero Zak phases. Moreover, the robustness of the interface state against disorder is validated, suggesting a viable method for studying underwater topological acoustic fields.