Condensats de Bose-Einstein dans un piège anisotrope

Fabrice Gerbier 1
1 laboratoire Charles Fabry de l'Institut d'Optique / Optique atomique
LCFIO - Laboratoire Charles Fabry de l'Institut d'Optique
Abstract : In this Thesis, we report on the study of Bose-Einstein condensates in anisotropic traps. First, the behavior of the thermal cloud is investigated for temperatures close to the condensation threshold. A shift in the critical temperature and a reduction of the condensed fraction due to interactions are observed, in good agreement with a Hartree-Fock theory of the mixed cloud. A second study focuses on the extraction and propagation of atom lasers created through radio-frequency output coupling. Measurements of the transverse divergence identify as the primary contributor the mean field exerted by the condensate on the outcoupled atoms. The third part is devoted to the study of phase fluctuations in very elongated (quasi-)condensates through Bragg spectroscopy of the momentum distribution. We observe a Lorentzian lineshape of the momentum distribution, characteristic of strongly phase-fluctuating samples. Measurements of the momentum width, along with the observation of suppressed density fluctuations when compared to a thermal-like distribution, confirm the validity of the Bogoliubov approach to describe low-dimensional quasi-condensates.
Document type :
Theses
Atomic Physics. Université Pierre et Marie Curie - Paris VI, 2003. French


https://pastel.archives-ouvertes.fr/tel-00003589
Contributor : Fabrice Gerbier <>
Submitted on : Friday, October 17, 2003 - 2:30:50 PM
Last modification on : Friday, March 27, 2015 - 4:02:23 PM

Identifiers

  • HAL Id : tel-00003589, version 2

Citation

Fabrice Gerbier. Condensats de Bose-Einstein dans un piège anisotrope. Atomic Physics. Université Pierre et Marie Curie - Paris VI, 2003. French. <tel-00003589v2>

Export

Share

Metrics

Consultation de
la notice

431

Téléchargement du document

136