Trapped Vortex Dynamics Implemented in Composite Bessel Beams

Abstract: The divergence-free nature of Bessel beams can be harnessed to effectively trap optical vortices in free space laser propagation. We show how to generate arbitrary vortex configurations in Bessel traps to investigate few-body vortex interactions within a dynamically-evolving fluid of light, which is a formal analog to a non-interacting Bose gas. We implement--theoretically and experimentally--initial conditions of vortex configurations first predicted in harmonically-trapped quantum fluids, in the limit of weak atomic interactions, and model and measure the resultant dynamics. These hard trap dynamics are distinct from the harmonic trap predictions due to the non-local interactions that occur among the hard wall boundary and steep phase gradients that nucleate other vortices. By simultaneously presenting experimental demonstrations with the theoretical proposal, we validate the potential application of using Bessel hard wall traps as testing grounds for engineering few-body vortex interactions within trapped, two-dimensional compressible fluids.