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Etude de gaz quantiques dégénérés quasi-unidimensionnels confinés par une micro-structure

Jean-Baptiste Trebbia 1
1 laboratoire Charles Fabry de l'Institut d'Optique / Optique atomique
LCFIO - Laboratoire Charles Fabry de l'Institut d'Optique
Abstract : This thesis presents experiments on degenerate Bose gases in the quasi-one dimensional regime. For this purpose we use an atom chip, microfabricated wires deposited on surfaces, to create very anisotropic traps in which we measured the statistical properties of an ultracold bosonic gas (Rubidium 87). For a classical gas, where the particles are statistically independent, density fluctuations are given by the atomic shot noise. At lower temperatures, the quantum nature of the particles appears (indistinguishable bosons), and an extra term has to be taken into account to describe the bosonic bunching. At low atomic densities, we observe these two kinds of behavior in good agreement with the ideal Bose gas predictions. At higher atomic densities, due to the energy cost of inter-atomic repulsive interactions, we observed a reduction of density fluctuations compared to the ideal case. This reduction reflects the transition to the quasi-condensate regime. To exploit the full potential of atom chip, atoms must often be close to the material structures which confine them. However, this proximity renders these devices highly sensitive to defects which produce roughness in the trapping potential. To circumvent this problem, we used a time-dependent trap where the atoms see the time-averaged potential without any roughness.
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Submitted on : Saturday, November 10, 2007 - 9:32:41 PM
Last modification on : Wednesday, October 14, 2020 - 3:56:54 AM
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Jean-Baptiste Trebbia. Etude de gaz quantiques dégénérés quasi-unidimensionnels confinés par une micro-structure. Matière Condensée [cond-mat]. Université Paris Sud - Paris XI, 2007. Français. ⟨tel-00186656⟩

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