Vortex creation, annihilation, and nonlinear dynamics in atomic vapors

We exploit techniques for generating vortices and controlling their interactions in an optical beam in a nonlinear atomic vapor. A precise control of the vortex positions allows us to observe strong interactions leading to vortex dynamics involving annihilations. With this improved controlled nonlinear system, we get closer to the pure hydrodynamic regime than in previous experiments while a wavefront sensor offers us a direct access to the fluid's density and velocity. Finally, we developed a relative phase shift method which mimics a time evolution process without changing nonlinear parameters. These observations are an important step toward the experimental implementation of a two-dimensional turbulent state.