  We study the expansion of a dilute ultracold sample of fermions initially
trapped in a anisotropic harmonic trap. The expansion of the cloud provides
valuable information about the state of the system and the role of
interactions. In particular the time evolution of the deformation of the
expanding cloud behaves quite differently depending on whether the system is in
the normal or in the superfluid phase. For the superfluid phase, we predict an
inversion of the deformation of the sample, similarly to what happens with
Bose-Einstein condensates. Viceversa, in the normal phase, the inversion of the
aspect ratio is never achieved, if the mean field interaction is attractive and
collisions are negligible.
