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Lévitation d'atomes par interférences et Transport bidimensionnel en présence de désordre

Martin Robert-De-Saint-Vincent 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 two experiments of atomic physics, realized on an ultra-cold sample of Rubidium 87. We tackle the topics of atom interferometry, and of the transport properties in disordered medium. In the first experiment, we demonstrate a technique for suspending atoms against gravity, which could help increase the interrogation time of atom interferometers. The atoms are periodically diffracted on a light standing wave, used as Bragg mirror to reflect the atoms and thus prevent their fall. However, when getting close to the thin grating limit, the matter wave-packet is splitted into many trajectories that periodically recombine. We show that the interference between these multiple components can be used to cancel the losses towards falling channels. This original interferometer could be an interesting alternative to suspend an inertial sensor or an atom clock in a limited volume, whilst allowing simultaneous measurement of the forces acting on the atoms. The second experiment is devoted to the study of the transport properties in a 2D disordered medium. In particular, matter wave interference can prevent the transport - a phenomenon known as Anderson Localization. The atoms are confined between two repulsive sheets of light, and the disorder is generated by a speckle pattern shined onto the cloud. We observe a diffusive expansion in these potentials, and extract diffusion coefficients in agreement with a numerical simulation. We then explore the dynamic at lower energies, where subdiffusion, classical trapping under the percolation threshold, and Anderson Localization may be observed. Finally, the study of the interplay between disorder and the Berezinskii-Kosterlitz-Thouless transition in 2D is now within reach.
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Submitted on : Wednesday, March 23, 2011 - 11:08:35 AM
Last modification on : Saturday, June 25, 2022 - 11:12:45 AM
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  • HAL Id : tel-00578701, version 2



Martin Robert-De-Saint-Vincent. Lévitation d'atomes par interférences et Transport bidimensionnel en présence de désordre. Matière Condensée [cond-mat]. Université Paris Sud - Paris XI, 2010. Français. ⟨tel-00578701v2⟩



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