Ground state of the polaron in an ultracold dipolar Fermi gas

An impurity atom immersed in an ultracold atomic Fermi gas can form a quasiparticle, so-called Fermi polaron, due to impurity-fermion interaction. We consider a three-dimensional homogeneous dipolar Fermi gas as a medium, where the interatomic dipole-dipole interaction (DDI) makes the Fermi surface deformed into a spheroidal shape, and, using a Chevy-type variational method, investigate the ground-state properties of the Fermi polaron: the effective mass, the momentum distribution of a particle-hole excitation, the drag parameter, and the medium-density modification around the impurity. These quantities are shown to exhibit spatial anisotropies in such a way as to reflect the momentum anisotropy of the background dipolar Fermi gas. We also give numerical results for the polaron properties at the unitarity limit of the impurity-fermion interaction in the case in which the impurity and fermion masses are equal. It has been found that the transverse effective mass and the transverse momentum drag parameter of the polaron both tend to decrease by similar to 10% when the DDI strength is raised from 0 up to around its critical value, while the longitudinal ones exhibit a very weak dependence on the DDI.

Automated summary

This study investigates the properties of Fermi polarons formed by impurity atoms in ultracold atomic Fermi gases, showing that these properties exhibit spatial anisotropies reflecting the momentum anisotropy of the background dipolar Fermi gas. The effective mass and momentum drag parameter of the polaron both tend to decrease by approximately 10% as the DDI strength increases up to its critical value, while the longitudinal properties show weak dependence on the DDI.