Universal Dynamical Response of a Driven Fermi Gas

We study the dynamics of the non- and weakly interacting Fermi gases subjected to an oscillating gradient potential with tunable frequency and amplitude. The applicability of linear response theory in a dissipationless system has recently generated theoretical interest. As we drive the gas, we observe interesting dynamics in the imaginary part of the density response function. At early times, the gas follows a linear-response behavior even under strong drives. At later times, the imaginary part stabilizes to a lower value under the balance of drive and dissipation. We further explore universal scalings of the dynamical response in terms of drive strength, drive period, and the relaxation time.