Observation of amplitude-driven nonreciprocity for energy guiding

TL;DR

This paper demonstrates how nonlinearity can induce amplitude-driven nonreciprocal energy localization in a non-Hermitian system, supported by theoretical, numerical, and experimental evidence, opening new avenues for non-reciprocal device design.

Contribution

It introduces a nonlinear extension to the Hatano-Nelson model, revealing amplitude-dependent skin modes and experimentally demonstrating these effects in acoustic metamaterials.

Findings

Amplitude-driven skin localization depends on power level.

Nonlinear couplings enable energy concentration at arbitrary points.

Experimental realization confirms theoretical predictions.

Abstract

The non-Hermitian skin effect is an intriguing physical phenomenon, in which all eigen-modes of a non-Hermitian lattice become localized at boundary regions. While such an exotic behavior has been demonstrated in various physical platforms, most realizations have been so far restricted to the linear regime. Here, we explore the cooperation between nonlinearity and the non-Hermitian skin effect, revealing extraordinary amplitude-driven skin localization dynamics. By introducing an extension to the Hatano-Nelson model where couplings inherent nonlinear behavior, we demonstrate the existence of unique amplitude-driven non-Hermitian skin modes capable of concentrating the energy of a source at any point of space, depending on the power level. Our theoretical model is supported by numerical simulations and experimental realization via a highly configurable acoustic metamaterial composed of active electroacoustic resonators. In all, our findings open up exciting paths for a new generation of non-reciprocal systems, in which nonlinearities serve as a strategic tuning knob to manipulate the guiding process.