We propose and experimentally realize a class of quasi-one-dimensional topological lattices whose unit cells are constructed by coupled multiple identical resonators, with uniform hopping and inversion symmetry. In the presence of coupling-path-induced effective zero hopping within the unit cells, the systems are characterized by complete multimerization with degenerate −1$-1$ energy edge states for open boundary condition. Su–Schrieffer–Heeger subspaces with fully dimerized limits corresponding to pairs of nontrivial flat bands are derived from the Hilbert spaces. In particular, topological bound states in the continuum (BICs) are inherently present in even multimer chains, manifested by embedding the topological bound states into a continuous band assured by bulk-boundary correspondence. Moreover, we experimentally demonstrate the degenerate topological edge states and topological BICs in radio-frequency circuits.

中文翻译：

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具有完全多聚化的多通道耦合诱导拓扑绝缘相

我们提出并实验实现了一类准一维拓扑晶格，其晶胞由多个相同谐振器耦合构成，具有均匀的跳跃和反演对称性。在晶胞内存在耦合路径诱导的有效零跳变的情况下，系统的特点是完全多聚化，具有开放边界条件的简并− 1$-1$能量边缘态。具有与非平凡平带对相对应的完全二聚化极限的 Su-Schrieffer-Heeger 子空间源自希尔伯特空间。特别是，连续体中的拓扑束缚态（BIC）本质上存在于甚至多聚体链中，这通过将拓扑束缚态嵌入到由体边界对应保证的连续带中来体现。此外，我们还通过实验证明了射频电路中的简并拓扑边缘态和拓扑 BIC。