Observation of Jones-Roberts solitons in a paraxial quantum fluid of light

TL;DR

This paper reports the experimental observation of Jones-Roberts solitons in a paraxial quantum fluid of light created in a hot rubidium vapor, demonstrating vortex dynamics, soliton formation, and coherence transfer.

Contribution

It provides the first experimental demonstration of Jones-Roberts solitons in a light-based quantum fluid, combining optical analogies with superfluid vortex dynamics.

Findings

Observation of vortex-antivortex dipole transition to rarefaction pulse

Calculation of vortex trajectories using ray optics analogy

Detection of coherence transfer from incompressible to compressible velocity

Abstract

We investigate the formation and dynamics of Jones-Roberts solitons in a smoothly inhomogeneous quantum fluid. To do so, we create a superfluid of light using paraxial, near-resonant laser beam propagating through a hot rubidium vapor. We excite a bounded vortex-antivortex dipole in the superfluid and observe its transition to a rarefaction pulse and back, in agreement with the seminal predictions of Jones and Roberts. Employing an analogy with ray optics, we calculate the trajectory of the interacting vortices, deriving an effective refractive index from the inhomogeneous fluid density. Finally, we examine analytically and experimentally the superfluid velocity correlations, observing a transfer of coherence from incompressible to compressible velocity of the quantum fluid, a direct signature of the dynamical conversion between vortices and rarefaction pulse.