Observation of edge solitons and transitions between them in a trimer circuit lattice

Abstract: In nonlinear topological systems, edge solitons either bifurcate from linear topological edge modes or emerge as nonlinearity-induced localized states without topological protection. While electric circuits (ECs) provide a platform for realizing various types of topological insulators, observation of edge solitons and transitions between them in EC lattices remains a challenging problem. Here, we realize quench dynamics in nonlinear ECs to experimentally demonstrate both topological and nontopological edge solitons in a trimer EC lattice and transitions between them. In the weakly-nonlinear regime, we observe antisymmetric (alias staggered) and symmetric (alias unstaggered) edge solitons bifurcating from the respective topological edge states in the linear limit. Under the action of strong nonlinearity, nontopological edge solitons with antisymmetric, symmetric, and asymmetric (strongly confined) internal structures are discovered. This work suggests new possibilities for exploring sophisticated nonlinear states and transitions between them in nonlinear topological systems.