Realization of higher-order topology in bilayer asymmetric Su–Schrieffer–Heeger topological electric circuits

In this Letter, we report on the realization of higher-order topology in electric circuit systems by generalizing the two-dimensional asymmetric Su–Schrieffer–Heeger (SSH) model to a bilayer model, which consists of two monolayer models that are directly coupled. Such a system inherits the topological properties of its monolayer counterparts and exhibits the existence of split edge states and corner states in a finite size. As well, the number of topological states is doubled due to the mirror-stacking operation. This work substantiates the existence of rich topological states in bilayer asymmetric SSH electric circuits and may inspire further research into higher-order topological insulators in artificial topological systems.