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Fermions et Bosons Dégénérés au Voisinage d'une Résonance de Feshbach : Production de Molécules et Solitons d'Ondes de Matière

Abstract : This thesis presents the results of experiments carried on bosonic 7Li and fermionic 6Li degenerate atomic gases of lithium. The N-body ground state of such gases depends strongly on the interatomic interaction whose intensity and nature, attractive or repulsive, can be tuned by means of a magnetic field in the vicinity of a Feshbach resonance. We use such a resonance in bosonic 7Li to produce the first matter wave soliton. It consists of a unidimensionnal atomic wave function in which an attractive
interaction compensates for the natural dispersion. Therefore it
travels without deformation. We produce a soliton from a 7Li Bose-Einstein condensate transferred into a one-dimensional optical
waveguide. Its characteristic propagation is observed over a distance of more than one millimeter. In an interacting 6Li fermionic gas we use another Feshbach resonance to form very efficiently ultra-cold and trapped 6Li2 molecules. Suprisingly, these dimers of fermions show a significantly longer lifetime than the dimers formed from bosons in a similar fashion. It is a consequence of the Pauli principle. This high stability allows us to produce a pure Bose-Einstein condensate of these bosonic molecules, achieving one of the limits of the fermionic superfluid.
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https://tel.archives-ouvertes.fr/tel-00006435
Contributor : Julien Cubizolles <>
Submitted on : Monday, July 12, 2004 - 1:50:35 PM
Last modification on : Thursday, December 10, 2020 - 12:39:07 PM
Long-term archiving on: : Monday, September 20, 2010 - 11:51:10 AM

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  • HAL Id : tel-00006435, version 2

Citation

Julien Cubizolles. Fermions et Bosons Dégénérés au Voisinage d'une Résonance de Feshbach : Production de Molécules et Solitons d'Ondes de Matière. Physique Atomique [physics.atom-ph]. Université Pierre et Marie Curie - Paris VI, 2004. Français. ⟨tel-00006435v2⟩

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