Mechanism for sound dissipation in a two-dimensional degenerate Fermi gas

We numerically study the transport properties of a two-dimensional Fermigas in a weakly and strongly interacting regimes, in the range oftemperatures close to the transition to a superfluid phase. For that weexcite sound waves in a fermionic mixture by using the phase imprintingtechnique, trace their evolution, and finally determine both their speedand attenuation. Our formalism incorporates thermal fluctuations via theground canonical ensemble description and with the help of Metropolisalgoritm. From numerical simulations we extract temperature dependenceof the sound velocity and diffusivity as well as the dependence on theinteraction strength. We emphasize the role of virtual vortex-antivortexpairs creation in the process of sound dissipation.