Radial quadrupole and scissors modes in trapped Fermi gases across the BCS phase transition

Abstract

The excitation spectra of the radial quadrupole and scissors modes of ultracold Fermi gases in elongated traps are studied across the BCS superfluid-normal phase transition in the framework of a transport theory for quasiparticles. In the limit of zero temperature, this theory reproduces the results of superfluid hydrodynamics, while in the opposite limit, above the critical temperature, it reduces to the collisionless Vlasov equation. In the intermediate temperature range, the excitation spectra have two or three broad peaks, respectively, which are roughly situated at hydrodynamic and collisionless frequencies, and whose strength is shifted from the hydrodynamic to the collisionless modes with increasing temperature. By fitting the time dependent quadrupole deformation with a damped oscillation of a single frequency, we can understand the "jump" of the frequency of the radial quadrupole mode as a function of interaction strength which has recently been reported by the Innsbruck group.

6 pages, v2: extended description of the theoretical method

References in corpus (7)

• Collective excitations of a degenerate gas at the BEC-BCS crossover
• Finite-Temperature Collective Dynamics of a Fermi Gas in the BEC-BCS Crossover
• Dynamics of a strongly interacting Fermi gas: the radial quadrupole mode
• Frequency and damping of the Scissors Mode of a Fermi gas
• Superfluid Expansion of a Strongly Interacting Fermi Gas
• Temperature and finite-size effects in collective modes of superfluid Fermi gases
• Coupling of hydrodynamics and quasiparticle motion in collective modes of superfluid trapped Fermi gases

Cited by in corpus (3)

• Collective modes of trapped Fermi gases with in-medium interaction
• Finite temperature damping of collective modes of a BCS-BEC crossover superfluid
• Coupled oscillator model of a trapped Fermi gas at the BEC-BCS crossover