Quadrupole oscillation in a dipolar Fermi gas: hydrodynamic vs collisionless regime

Abstract

The surface quadrupole mode of an harmonically trapped dipolar Fermi gas is studied in both the hydrodynamic and collisionless regimes. The anisotropy and long range effects of the dipolar force as well as the role of the trapping geometry are explicitly investigated. In the hydrodynamic regime the frequency is always slightly smaller than the $\sqrt{2}{\omega }_{\perp }$ value holding for gases interacting with contact interactions. In the collisionless regime the frequency can be either pretty smaller or larger than the non-interacting value $2{\omega }_{\perp }$, depending on the cloud aspect ratio. Our results suggest that the frequency of the surface quadrupole oscillation can provide a useful test for studying, at very low temperatures, the transition between the normal and the superfluid phase and, in the normal phase at higher temperatures, the crossover between the collisional and collisionless regimes. The consequences of the anisotropy of the dipolar force on the virial theorem are also discussed.

8 pages, 4 figures

References in corpus (12)

• Theory of ultracold Fermi gases
• A High Phase-Space-Density Gas of Polar Molecules
• Bose-Einstein condensation of chromium
• Bogoliubov modes of a dipolar condensate in a cylindrical trap
• Exact hydrodynamics of a trapped dipolar Bose-Einstein condensate
• Phase space deformation of a trapped dipolar Fermi gas
• Expansion dynamics of a dipolar Bose-Einstein condensate
• Vortices in dipolar condensates with dominant dipolar interactions
• Dynamics of a strongly interacting Fermi gas: the radial quadrupole mode
• Collective excitation frequencies and stationary states of trapped dipolar Bose-Einstein condensates in the Thomas-Fermi regime
• Hydrodynamic excitations of trapped dipolar fermions
• Center motions of nonoverlapping condensates coupled by long-range dipolar interaction in bilayer and multilayer stacks

Cited by in corpus (5)

• Collective excitations of quasi-two-dimensional trapped dipolar fermions: transition from collisionless to hydrodynamic regime
• Second-order interaction corrections to the Fermi surface and the quasiparticle properties of dipolar fermions in three dimensions
• Collective excitations of a harmonically trapped, two-dimensional, spin-polarized dipolar Fermi gas in the hydrodynamic regime
• Time-of-flight expansion of trapped dipolar Fermi gases: From the collisionless to the hydrodynamic regime
• Study of a degenerate dipolar Fermi gas of 161Dy atoms