Nonreciprocal localization of ultrasound in a viscous medium with asymmetric scatterers

TL;DR

This study demonstrates nonreciprocal ultrasound localization in a viscous medium with asymmetric scatterers, revealing direction-dependent sound transmission and localization properties influenced by system symmetry breaking.

Contribution

It introduces a phononic crystal with asymmetric scatterers to achieve nonreciprocal sound localization, highlighting the role of dissipative losses and asymmetry in breaking PT-symmetry.

Findings

Exponential weak transmission along the disordered direction.

Extended wave propagation in the ordered direction.

Different localization lengths for opposite directions.

Abstract

A two-dimensional phononic crystal with asymmetric scatterers is used for the study of Anderson localization of sound along one-dimensional disorder produced by random orientation of metallic rods. An exponentially weak transmission of ultrasound is demonstrated for the waves propagating along the direction of disorder. In the perpendicular direction where the scatterers are ordered, sound propagates as extended wave. The {\it PT}-symmetry of the system is broken by dissipative viscous losses and asymmetric shape of the scatterers. Nonreciprocal transmission of sound is observed for both, ordered and disordered, directions. In the localized regime, the nonreciprocity is manifested through different values of localization length for sound propagating in the opposite directions.