Higher-order topological states mediated by long-range coupling in -symmetric lattices

NA Olekhno, AD Rozenblit, VI Kachin… - arXiv preprint arXiv …, 2021 - arxiv.org
arXiv preprint arXiv:2103.08980, 2021arxiv.org
Topological physics opens a door towards flexible routing and resilient localization of waves
of various nature. Recently proposed higher-order topological insulators provide advanced
control over wave localization in the structures of different dimensionality. In many cases, the
formation of such higher-order topological phases is governed by the lattice symmetries,
with kagome and breathing honeycomb lattices being prominent examples. Here, we design
and experimentally realize the resonant electric circuit with $ D_4 $ symmetry and additional …
Topological physics opens a door towards flexible routing and resilient localization of waves of various nature. Recently proposed higher-order topological insulators provide advanced control over wave localization in the structures of different dimensionality. In many cases, the formation of such higher-order topological phases is governed by the lattice symmetries, with kagome and breathing honeycomb lattices being prominent examples. Here, we design and experimentally realize the resonant electric circuit with symmetry and additional next-nearest-neighbor couplings. As we prove, a coupling of the distant neighbors gives rise to an in-gap corner state. Retrieving the associated invariant directly from the experiment, we demonstrate the topological nature of the designed system, revealing the role of long-range interactions in the formation of topological phases. Our results thus highlight the distinctions between tight-binding systems and their photonic counterparts with long-range couplings.
arxiv.org