Topological transport of sound mediated by spin-redirection geometric phase

TL;DR

This paper demonstrates how spin-redirection geometric phases can induce topological transport of sound, enabling control over scalar wave flow through experimental and theoretical analysis of sound vortices.

Contribution

It introduces the concept of spin-redirection geometric phase effects in airborne sound, a scalar wave, and shows their potential for manipulating sound propagation.

Findings

Experimental verification of spin-redirection geometric phase effects in sound

Demonstration of helical sound transport controlled by geometric phases

Potential applications in sound wave manipulation and control

Abstract

When a dynamic system undergoes a cyclic evolution, a geometric phase that depends only on the path traversed in parameter space can arise in addition to the normal dynamical phase. These geometric phases have profound impacts in both quantum and classical physics. In addition to the geometric phase associated with band structures in reciprocal space that has led to the discovery of topological insulators, the spin-redirection geometric phase induced by the $SO$(3) rotation of states in real space can also give rise to intriguing phenomena such as the photonic analog of the spin Hall effect. By exploiting the orbital angular momentum of sound vortices, we theoretically and experimentally demonstrate the spin-redirection geometric phase effects in airborne sound, which is a scalar wave without spin. We show that these effects, associated with the helical transport of sound, can be used to control the flow of sound. This finding opens new possibilities for the manipulation of scalar wave propagation by exploiting spin-redirection geometric phases.