Dynamics of Vortices and Dark Solitons in Polariton Superfluids

In this chapter we describe some observations linked with turbulence in quantum fluids of polaritons. We imprint a given velocity and density to the polariton fluid by using an appropriate pulse intensity and wavevector. The flow is then perturbed by a natural defect or more interestingly, by engineered traps with a well defined potential change. The flow of the fluid is measured in a time resolved fashion through the use of homodyne detection. Both the intensity and the phase of the fluid can then be retrieved with a picosecond resolution. This allows observing the nucleation of quantized vortices, with the appropriate 2π phase shift around the core, or the growth of dark solitons in the wake of the obstacle. The dark solitons are observed to decay into vortex streets. Our results are compared to dynamical solutions of the Gross-Pitaevskii equation and a very good agreement is obtained allowing us to hold good confidence in our interpretation.