Higher-order topological insulators (HOTIs) capable of hosting multi-dimensional topological states have been considered as a significant platform for wave regulation. Here, based on a “breathing” kagome lattice composed of coupled tube resonators, we demonstrate the topological phase transition induced by tuning the nearest-neighbor interactions of the tubes. Crucially, beyond the nontrivial bulk polarization, we unveil that the behaviors of the higher-order topological states are also affected by the boundary conditions, which enriches the design of the desired HOTIs. Along these lines, we propose two prototypes of acoustic topological devices and experimentally exhibit two promising applications of the topological corner states for frequency-selected energy harvesting in different conditions. Our work extends the applications of the higher-order topological states in resonant acoustic systems and provides diverse routes for designing topological devices on a subwavelength scale.

中文翻译：

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拓扑声谐振器阵列中的边界相关角状态

能够承载多维拓扑状态的高阶拓扑绝缘体（HOTI）已被认为是波浪调节的重要平台。在这里，基于由耦合管谐振器组成的“呼吸”kagome 晶格，我们展示了通过调整管的最近邻相互作用引起的拓扑相变。至关重要的是，除了非平凡的体极化之外，我们揭示了高阶拓扑态的行为也受边界条件的影响，这丰富了所需 HOTI 的设计。沿着这些思路，我们提出了两种声学拓扑器件的原型，并通过实验展示了拓扑角态在不同条件下用于频率选择能量收集的两种有前景的应用。