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

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 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 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 applications in topological switching and sensing through the simultaneous non-trivial interplay of skin and topological boundary localizations. Even though exploiting skin-topological effects in topological insulators is attractive for topological switch design, current research has focused on theoretical demonstrations. Here, the authors experimentally demonstrate higher-order topological skin effects in nonreciprocal topoelectrical circuits.

Automated summary

This work reports the experimental realizations of hybrid higher-order skin-topological effect in non-reciprocal topoelectrical circuits, showcasing the dynamic interplay of non-reciprocal pumping and topological localization to form various states. Through a highly versatile and scalable circuit platform, the authors demonstrate higher-order topological skin effects, paving the way for applications in topological switching and sensing.