Acoustic vortex beams in synthetic magnetic fields

Area of Science:

• Acoustics
• Quantum Optics
• Fluid Dynamics

Background:

• Vortex beams carry orbital angular momentum, analogous to electron beams in magnetic fields.
• Synthetic magnetic fields offer novel ways to control wave propagation.

Purpose of the Study:

• To investigate the propagation of acoustic vortex beams in synthetic magnetic fields.
• To explore the generation of specific synthetic magnetic field configurations for acoustic vortex beams.
• To identify differences between acoustic and electron vortex beam behavior.

Main Methods:

• Generating uniform and Aharonov-Bohm flux tube synthetic magnetic fields using a fluid in circulating cylinders.
• Analyzing the propagation of Laguerre-Gauss and Bessel acoustic vortex beams.
• Comparing acoustic vortex beam behavior with electron vortex beams in magnetic fields.

Main Results:

• Successfully generated two synthetic magnetic field configurations for acoustic vortex beams.
• Observed qualitative differences in non-paraxial acoustic vortex beam propagation compared to electron beams.
• Identified the sensitivity of acoustic wave pressure and velocity components to the sign of orbital angular momentum and magnetic field.

Conclusions:

• The vectorial nature of acoustic velocity fields leads to unique behaviors not seen in electron vortex beams.
• Analogies between optical, electron, and acoustic vortex beams can be limited in the presence of external vector potentials.
• This work opens new avenues for controlling acoustic waves using synthetic magnetic fields.