Topological Acoustics

TL;DR

This paper introduces a new theory of topological fluid acoustics, demonstrating how circulating fluids can create one-way sound propagation that is robust against defects, with potential applications in acoustic devices.

Contribution

It develops a novel theoretical framework for topological acoustics in fluids and proposes a practical scheme for realizing topological edge states in acoustic structures.

Findings

Topological fluid acoustics enable disorder-free one-way sound propagation.

Circulating fluids can induce topological edge states in acoustic systems.

Potential applications include acoustic isolators, modulators, and transducers.

Abstract

The manipulation of acoustic wave propagation in fluids has numerous applications, including some in everyday life. Acoustic technologies frequently develop in tandem with optics, using shared concepts such as waveguiding and metamedia. It is thus noteworthy that an entirely novel class of electromagnetic waves, known as topological edge states, has recently been demonstrated. These are inspired by the electronic edge states occurring in topological insulators, and possess a striking and technologically promising property: the ability to travel in a single direction along a surface without backscattering, regardless of the existence of defects or disorder. Here, we develop an analogous theory of topological fluid acoustics, and propose a scheme for realizing topological edge states in an acoustic structure containing circulating fluids. The phenomenon of disorder-free one-way sound propagation, which does not occur in ordinary acoustic devices, may have novel applications for acoustic isolators, modulators, and transducers.