All-optical modeling of superfluid shock waves

Lene Vestergaard Hau

Johan W. Bakker, Herman van Kempen, Huub W. M. Salemink +1 more

Senne Van Loon, Wout Van Alphen, Jacques Tempere +1 more

We study the propagation of shock waves in superfluid Fermi gases in the BEC-BCS crossover. Unlike in other superfluid systems, where shock waves have already been studied and observed, Fermi gases can exhibit a subsonic dispersion relation for which the shock wave pattern appears at the tail of the wavefront. We show that this property can be used to distinguish between a subsonic and a supersonic dispersion relation at unitarity.

P. V. E. McClintock

Matteo Conforti

Light flow in nonlinear media can exhibit quantum hydrodynamical features which are profoundly different from those of classical fluids. We show that rather extremes regime of quantum hydrodynamics can be accessed by exploring two paradigmatic problems in fluid dynamics. The first one is the piston problem for light, and its generalization, named after the celebrated mathematician Riemann, where the piston acts on a concomitant abrupt change of photon density. Our experiment reveals regimes featuring optical rarefaction (retracting piston) or shock (pushing piston) wave pairs, and most importantly the transition to a peculiar type of flow, occurring above a precise critical piston velocity, where the light shocks are smoothly interconnected by a large contrast, periodic, fully nonlinear wave. The second one is the temporal photonic analogue of the dam-break phenomenon for shallow water by exploiting a fiber optics setup. We clearly observe the decay of the step-like input (photonic dam) into a pair of oppositely propagating rarefaction wave and dispersive shock wave. Our results show evidence for a critical transition of the dispersive shock into a self-cavitating state.Our results show that fiber-based optical systems are peerless testbeds to investigate the extension of gas dynamics problems to superfluid regimes by taking benefit of the analogy between optics and fluid dynamics supported by the universality of the nonlinear Schrodinger equation.

H. Fröhlich