Effects of trap anisotropy on impurity scattering regime in a Fermi gas

Abstract

We evaluate the low-lying oscillation modes and the ballistic expansion properties of a harmonically trapped gas of fermionic K40 atoms containing thermal Rb87 impurities as functions of the anisotropy of the trap. Numerical results are obtained by solving the Vlasov-Landau equations for the one-body phase-space distribution functions and are used to test simple scaling Ansatzes. Starting from the gas in a weak impurity-scattering regime inside a spherical trap, the time scales associated to motions in the axial and azimuthal directions enter into competition as the trap is deformed to an elongated cigar-like shape. This competition gives rise to coexistence of collisionless and hydrodynamic behaviors in the low-lying surface modes of the gas as well as to a dependence of the aspect ratio of the expanding cloud on the collision time.

6 pages, 4 figures, accepted for publication in Phys. Rev. A

References in corpus (4)

• Observation of the Pairing Gap in a Strongly Interacting Fermi Gas
• Collective excitations of a degenerate gas at the BEC-BCS crossover
• Collective excitations in trapped boson-fermion mixtures: from demixing to collapse
• Effects of collisions against thermal impurities in the dynamics of a trapped fermion gas