Properties of transient superfluids

While properties of equilibrium superfluids are well understood, recent pump probe experiments make it imperative to understand transport in a highly non-equilibrium setting. We first address the following question: If fermions are initially in a normal phase, and the interactions are quenched so that the system is near a superconducting critical point, what are the transport properties in the transient regime? Through a quantum kinetic equation that accounts for scattering off of the temporally growing critical fluctuations, we show the appearance of aging physics in the optical conductivity, and the gradual appearance of a highly conducting channel indicated by the growth in time of the
low-frequency conductivity. Our results depend on only a few material parameters.

We also address how by tuning the properties of the non-equilibrium environment such as the amplitude and frequency of a circularly polarized laser, one may tune the symmetry of the superconducting order-parameter, making it vary from a time-reversal broken d+id form to a more generic s-wave form.

This work was done in collaboration with Yonah Lemonik, Daniel Yates, and Hossein Dehghani.