Acoustic vortex beams in synthetic magnetic fields

TL;DR

This paper explores how acoustic vortex beams behave in synthetic magnetic fields, revealing unique effects due to their vectorial nature and differences from electron vortex beams, with potential implications for wave physics.

Contribution

It demonstrates the generation of specific acoustic vortex configurations in synthetic magnetic fields and highlights qualitative differences from electron vortex beams due to vectorial effects.

Findings

Generation of uniform synthetic magnetic field with Laguerre-Gauss modes

Observation of Bessel beams in Aharonov-Bohm flux tube configuration

Qualitative differences in non-paraxial beams compared to electron vortex beams

Abstract

We analyze propagation of acoustic vortex beams in longitudinal synthetic magnetic fields. We show how to generate two field configurations using a fluid contained in circulating cylinders: a uniform synthetic magnetic field hosting Laguerre-Gauss modes, and an Aharonov-Bohm flux tube hosting Bessel beams. For non-paraxial beams we find qualitative differences from the well-studied case of electron vortex beams in magnetic fields, arising due to the vectorial nature of the acoustic wave's velocity field. In particular, the pressure and velocity components of the acoustic wave can be individually sensitive to the relative sign of the beam orbital angular momentum and the magnetic field. Our findings illustrate how analogies between optical, electron, and acoustic vortex beams can break down in the presence of external vector potentials.