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arXiv · 2007.15288

Realization of the square-root higher-order topological insulator in electric circuits

Lingling Song·Huanhuan Yang·Yunshan Cao·Peng Yan
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Abstract

Higher-order topological insulator (HOTI) represents a new phase of matter, the characterization of which goes beyond the conventional bulk-boundary correspondence and is attracting significant attention by the broad community. Using a square-root operation, it has been suggested that a square-root HOTI may emerge in a hybrid honeycomb-kagome lattice. Here, we report the first experimental realization of the square-root HOTI in topological LC circuits. We show theoretically and experimentally that the square-root HOTI inherits the feature of wave function from its parent, with corner states pinned to non-zero energies. The topological feature is fully characterized by the bulk polarization. To directly measure the finite-energy corner modes, we introduce extra grounded inductors to each node. Our results experimentally substantiate the emerging square-root HOTI and pave the way to realizing exotic topological phases that are challenging to observe in condensed matter physics.

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Lingling Song, Huanhuan Yang, Yunshan Cao, Peng Yan. 2020-07-30. Realization of the square-root higher-order topological insulator in electric circuits. https://doi.org/10.1021/acs.nanolett.0c03049

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