Superradiant Amplification of Acoustic Beams via Medium Rotation

TL;DR

This paper theoretically demonstrates how superradiant amplification of acoustic beams carrying orbital angular momentum can occur in a rotating absorbing medium, suggesting a new way to amplify or absorb sound non-reciprocally.

Contribution

It introduces a theoretical framework for acoustic superradiance and proposes a feasible experimental setup using current technology.

Findings

Superradiant amplification of acoustic beams is theoretically possible.

Rotating absorbing media can non-reciprocally amplify or absorb acoustic waves.

Potential for experimental realization with existing technology.

Abstract

Superradiant gain is the process in which waves are amplified via their interaction with a rotating body, examples including evaporation of a spinning black hole and electromagnetic emission from a rotating metal sphere. In this paper we elucidate theoretically how superradiance may be realized in the field of acoustics, and predict the possibility of non-reciprocally amplifying or absorbing acoustic beams carrying orbital angular momentum by propagating them through an absorbing medium that is rotating. We discuss a possible geometry for realizing the superradiant amplification process using existing technology.