Collective Motion of Polarized Dipolar Fermi Gases in the Hydrodynamic Regime

TL;DR

This paper develops a variational Hartree-Fock model to study the collective motion of polarized dipolar Fermi gases in the hydrodynamic regime, revealing anisotropic oscillations and momentum distribution behaviors.

Contribution

It introduces a novel theoretical approach to describe the dynamical properties of polarized dipolar Fermi gases in the hydrodynamic regime.

Findings

Dipole-dipole interactions cause anisotropic breathing oscillations.

Momentum distribution becomes isotropic after trap release.

Particle density remains anisotropic post-expansion.

Abstract

Recently, a seminal STIRAP experiment allowed the creation of 40K-87Rb molecules in the rovibrational ground state [K.-K. Ni et al., Science 322, 231 (2008)]. In order to describe such a polarized dipolar Fermi gas in the hydrodynamic regime, we work out a variational time-dependent Hartree-Fock approach. With this we calculate dynamical properties of such a system as, for instance, the frequencies of the low-lying excitations and the time-of-flight expansion. We find that the dipole-dipole interaction induces anisotropic breathing oscillations in momentum space. In addition, after release from the trap, the momentum distribution becomes asymptotically isotropic, while the particle density becomes anisotropic.