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.
We have analyzed Coulomb drag between currents of interacting electrons in two parallel one-dimensional conductors of finite length
L attached to external reservoirs. For strong coupling, the relative fluctuations of electron density in the conductors acquire energy gap
M. At energies larger than $\ensuremath{\Gamma}\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}\mathrm{const}\ifmmode\times\else\texttimes\fi{}{v}_{\ensuremath{-}}\mathrm{exp}(\ensuremath{-}LM/{v}_{\ensuremath{-}})/L+{\ensuremath{\Gamma}}_{+}$, where ${\ensuremath{\Gamma}}_{+}$ is the impurity scattering rate, and, for $L>{v}_{\ensuremath{-}}/M$, where ${v}_{\ensuremath{-}}$ is the fluctuation velocity, the gap leads to an ``ideal'' drag with almost equal currents in the conductors. At low energies the drag is suppressed by coherent instanton tunneling, and the zero-temperature transconductance vanishes, indicating the Fermi-liquid behavior.