Observation of hybrid higher-order skin-topological effect in non-Hermitian topolectrical circuits

TL;DR

This paper experimentally demonstrates a novel hybrid higher-order skin-topological effect in non-Hermitian topolectrical circuits, revealing complex boundary states resulting from the interplay of non-reciprocal pumping and topological localization.

Contribution

First experimental realization of hybrid higher-order skin-topological effects in non-Hermitian topolectrical circuits, showcasing new boundary states with no Hermitian or lower-dimensional analogs.

Findings

Demonstration of 2D and 3D skin-topological hybrid states

Observation of higher-order non-Hermitian skin states

Potential applications in topological switching and sensing

Abstract

Robust boundary states epitomize how deep physics can give rise to concrete experimental signatures with technological promise. Of late, much attention has focused on two distinct mechanisms for boundary robustness - topological protection, as well as the non-Hermitian skin effect. In this work, we report the first experimental realizations of hybrid higher-order skin-topological effect, in which the skin effect selectively acts only on the topological boundary modes, not the bulk modes. Our experiments, which are performed on specially designed non-reciprocal 2D and 3D topolectrical circuit lattices, showcases how non-reciprocal pumping and topological localization dynamically interplays to form various novel states like 2D skin-topological, 3D skin-topological-topological hybrid states, as well as 2D and 3D higher-order non-Hermitian skin states. Realized through our highly versatile and scalable circuit platform, theses states have no Hermitian nor lower-dimensional analog, and pave the way for new applications in topological switching and sensing through the simultaneous non-trivial interplay of skin and topological boundary localizations.