Plasmon-polaritonic quadrupole topological insulators
Ying Chen, Zhi‐Kang Lin, Huanyang Chen, Jian‐Hua Jiang
Abstract
Quadrupole topological insulator is a symmetry-protected higher-order topological phase with the intriguing topology of Wannier bands, which, however, has not yet been realized in plasmonic metamaterials. Here, we propose a lattice of plasmon-polaritonic nanocavities which can realize quadrupole topological insulators by exploiting the geometry-dependent sign reversal of the couplings between the daisylike nanocavities. The designed system exhibits various topological and trivial phases as characterized by the nested Wannier bands and the topological quadrupole moment which can be controlled by the distances between the nanocavities. Our study opens a pathway toward plasmonic topological metamaterials with quadrupole topology.