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Refroidissement et piégeage d'atomes de césium dans des structures lumineuses à faible taux de diffusion

Abstract : We experimentally study cooling and trapping of cesium atoms in low scattering rate light structures. We investigate gray molasses for which the cooling occurs on a Jf → Je = Jf - 1 transition with a blue detuning of the laser beams (laser frequency higher than atomic frequency). Because the atoms are pumped m states which are weakly coupled to the light field, the photon scattering rate is reduced and the minimum temperature (~ 1 μK) is three times lower than in a conventional molasses Confinement of these cold atoms is made using a far-detuned dipole trap created by an intense YAG laser beam. In a first step, the atoms are trapped m the waist of single focused Gaussian beam. The atomic cloud has a cylindrical shape with a strong tranverse confinement (rms size of ~ 6 μm) and a peak density of 10^12 at/cm^3. The optical density along the trapping beam is estimated to 500. We show that in this anisotropic geometry the heating due to photon multiple scattenng within the atomic cloud is greatly reduced. Then, by imaging onto the cold atoms a transmission grating illuminated by the YAG beam we create a far-detuned optical lattice with a 29 μm period (rms width of ~ 3 μm in a lattice site). Absorption images give a direct observation of the atomic localization. The lattice contains no vacancies. Because of the Talbot effect, the confinement is three-dimensional and leads to a peak density greater than 10^13 at/cm^3 and a phase space density of ~ 10^-3. The strong confinement and the high atomic densities that we have achieved open the way for various applications.
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https://tel.archives-ouvertes.fr/tel-00011783
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Submitted on : Tuesday, March 7, 2006 - 12:58:40 PM
Last modification on : Thursday, October 29, 2020 - 3:01:16 PM
Long-term archiving on: : Saturday, April 3, 2010 - 9:02:24 PM

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  • HAL Id : tel-00011783, version 1

Citation

Denis Boiron. Refroidissement et piégeage d'atomes de césium dans des structures lumineuses à faible taux de diffusion. Physique Atomique [physics.atom-ph]. Université Pierre et Marie Curie - Paris VI, 1998. Français. ⟨tel-00011783⟩

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