Eur. Phys. J. D 54, 667-682 (2009)
https://doi.org/10.1140/epjd/e2009-00182-9

Rotating Fermi gases in an anharmonic trap

¹ Department of Physics, University of Arizona, Tucson, AZ, 85721, USA
² Institut für Theoretische Physik, Freie Universität Berlin, Arnimallee 14, 14195 Berlin, Germany
³ Fachbereich Physik, Universität Duisburg-Essen, Lotharstrasse 1, 47048 Duisburg, Germany

Corresponding authors: ^a howek@email.arizona.edu - ^b lima@physik.fu-berlin.de - ^c axel.pelster@fu-berlin.de

Received: 18 December 2008
Revised: 15 April 2009
Published online: 23 June 2009

Abstract

Motivated by recent experiments on rotating Bose-Einstein condensates, we investigate a rotating, polarized Fermi gas trapped in an anharmonic potential. We apply a semiclassical expansion of the density of states in order to determine how the thermodynamic properties depend on the rotation frequency. The accuracy of the semiclassical approximation is tested and shown to be sufficient for describing typical experiments. At zero temperature, rotating the gas above a given frequency Ω_DO leads to a `donut'-shaped cloud which is analogous to the hole found in two-dimensional Bose-Einstein condensates. The free expansion of the gas after suddenly turning off the trap is considered and characterized by the time and rotation frequency dependence of the aspect ratio. Temperature effects are also taken into account and both low- and high-temperature expansions are presented for the relevant thermodynamical quantities. In the high-temperature regime a virial theorem approach is used to study the delicate interplay between rotation and anharmonicity.