Non-Hermitian second-order topology induced by resistances in electric circuits

The study of topological states in electric circuits is developing rapidly recently and forming the field of topoelectrical circuits. As both the loss and gain can be easily introduced and tuned in electric circuits, it permits flexible and accurate fabrications of non-Hermitian systems. Loss is generally considered negative in electric circuits, as it weakens the electrical signals. However, we show here that a non-Hermitian second-order topological phase can be realized in electric circuits by taking advantage of loss. We observe the gapped edge states and in-gap corner states in experiment. Our system provides a readily accessible platform to explore the non-Hermitian-induced topological phases.