Observation of Impurity-Induced Scale-Free Localization in a Disordered Non-Hermitian Electrical Circuit

TL;DR

This paper experimentally demonstrates impurity-induced scale-free localization in a disordered non-Hermitian electrical circuit, revealing a new type of eigenstate accumulation distinct from the non-Hermitian skin effect.

Contribution

It introduces the first experimental observation of scale-free localization caused by impurities in non-Hermitian circuits, expanding understanding of skin effects.

Findings

Observation of anomalous scale-free eigenstate accumulation

Opposite localization direction to bulk hopping

Impurity effects in non-Hermitian electrical circuits

Abstract

One of unique features of non-Hermitian systems is the extreme sensitive to their boundary conditions, e.g., the emergence of non-Hermitian skin effect (NHSE) under the open boundary conditions, where most of bulk states become localized at the boundaries. In the presence of impurities, the scale-free localization can appear, which is qualitatively distinct from the NHSE. Here, we experimentally design a disordered non-Hermitian electrical circuits in the presence of a single non-Hermitian impurity and the nonreciprocal hopping. We observe the anomalous scale-free accumulation of eigenstates, opposite to the bulk hopping direction. The experimental results open the door to further explore the anomalous skin effects in non-Hermitian electrical circuits.