Tuning dissipation and excitations in superfluid Fermi gases with a moving impurity

We develop a method to extract the dissipation for a heavy moving impurity immersed in superfluid Fermi gases, which may serve as a theoretical model to explain relevant experiments. The drag force is derived analytically. As a reward, we are able to extract the density-density correlation function, from which density excitations of the system are carefully examined. We show that dissipations through drag force is associated with two types of excitations, one being single-particle and the other being collective. We map out the critical velocity for dissipation across the Bose-Einstein condensate-Bardeen-Cooper-Schrieffer (BEC-BCS) crossover, consistent with existing experiments. For a magnetic impurity, we show that the dissipation is immune to collective excitations. Our study clearly manifests that dissipation and associated excitations can be controlled by coupling superfluid Fermi gases with a moving impurity, and paves the way for further exploring the intriguing realm of nonequilibrium phenomena and dissipation dynamics.