Observation of hybridized corner states induced by inter-layer interactions

Abstract We demonstrate theoretically and experimentally that the inter-layer nearest-neighbor (NN) coupling in a hybrid valley crystal plays a critical role in the emergence of a new-type corner state --- hybridized corner state, which splits from the edge states, possessing a hybridized features of the type-I and type-II corner states, but with quite different physical origin. We further show that this hybridized corner state is reconfigurable, just simply by tuning the inter-layer NN coupling. In contrast to the previously proposed methods to achieve reconfigurable higher-order topological states, for which globe modulations are commonly required in the whole lattice systems, here only local modulations are applied to the inter-layer NN couplings. This approach based on standard tight-binding formalism is general, and can be realized in a wide variety of fields, including photonics, phononics, and microwaves, paving the way for topological switching, energy storage, and other functional photonic devices based on reconfigurable higher-order corner states.