Dynamic Manipulation of Non-Hermitian Skin Effect through Frequency in Topolectrical Circuits

TL;DR

This paper demonstrates a frequency-controlled switchable non-Hermitian skin effect in topolectrical circuits, enabling on/off control of eigenstate localization without circuit modifications, with potential applications in sensors.

Contribution

It introduces a novel method to toggle the non-Hermitian skin effect in topolectrical circuits solely by adjusting the driving frequency.

Findings

NHSE is activated when frequency exceeds a critical value.

NHSE can be turned off below the critical frequency, even in coupled chains.

Frequency control offers a new way to manipulate eigenstate localization.

Abstract

One of the most fascinating phenomena in non-Hermitian systems is the extensive accumulation of the bulk eigenstates under open-boundary conditions which is known as the non-Hermitian skin effect (NSHE). Here, we propose a switchable NHSE in a topolectrical (TE) set-up which can be turned on or off simply by varying the driving frequency without any modification to the physical circuit. Specifically, we consider a coupled system consisting of two non-Hermitian Hatano-Nelson chains where each node of one chain is connected to neighboring node of the other chain via resistive couplings with opposite signs for the two coupling directions. Interestingly, the NHSE is switched on only if the driving frequency is greater than a certain critical frequency. Conversely, the NHSE in the coupled system is switched off when the frequency falls below the critical value, even though the individual uncoupled chains still exhibit the NHSE. This frequency-controlled NHSE may pave the way for many possible applications including non-Hermitian sensors where the driving frequency can manipulate the current and voltage localization.