title: Collective excitations of a dipolar Bose-Einstein condensate.
abstract: We have measured the effect of dipole-dipole interactions on the frequency of a collective mode of a Bose-Einstein condensate. At relatively large numbers of atoms, the experimental measurements are in good agreement with zero temperature theoretical predictions based on the Thomas-Fermi approach. Experimental results obtained for the dipolar shift of a collective mode show a larger dependency to both the trap geometry and the atom number than the ones obtained when measuring the modification of the condensate aspect ratio due to dipolar forces. These findings are in good agreement with simulations based on a Gaussian ansatz.
authors.affiliation: Laboratoire de Physique des Lasers, CNRS UMR 7538, Université Paris 13, 99 Avenue J.-B. Clément, 93430 Villetaneuse, France.
authors.forename: G
authors.initials: G
authors.lastname: Bismut
authors.forename: B
authors.initials: B
authors.lastname: Pasquiou
authors.forename: E
authors.initials: E
authors.lastname: Maréchal
authors.forename: P
authors.initials: P
authors.lastname: Pedri
authors.forename: L
authors.initials: L
authors.lastname: Vernac
authors.forename: O
authors.initials: O
authors.lastname: Gorceix
authors.forename: B
authors.initials: B
authors.lastname: Laburthe-Tolra