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Deux outils pour l'optique atomique : Jet intense d'hélium métastable et Miroir à onde évanescente exaltée

Guillaume Labeyrie 1
1 laboratoire Charles Fabry de l'Institut d'Optique / Optique atomique
LCFIO - Laboratoire Charles Fabry de l'Institut d'Optique
Abstract : This thesis describes two tools for atom optics experiments. The first one is a bright metastable helium beam. The source of helium atoms is a liquid-nitrogen cooled supersonic beam. Several steps of laser manipulation are used to increase the intensity of the atomic beam. First, the diverging beam is collimated by applying a transverse 2D optical molasses. The atomic beam is then dece1erated using the Zeeman slowing technique. Two important consequences arise from the small mass ofthe helium atom : the stopping distance is large (~ 2 m), and the transverse spreading of the beam during the slowing process is significant. Thus, a spatial recompression ofthe atomic beam is needed. This is achieved by a new device, called a "concentrator". This device focuses the atomic beam on its axis. The atomic intensity at the focal point is increased by a factor 20. The transverse position ofthe focal point can be scaned by applying a time-dependent magnetic field. The second too1 is an evanescent-wave atomic mirror. To avoid spontaneous emission during reflection, which destroys the coherence ofthe reflected De Broglie wave, one needs a large intensity in the evanescent wave. A resonant system, based on thin dielectric 1ayers deposited on a prism, is used to enhance the intensity in the evanescent wave by more than 3 orders of magnitude. An optical technique ofana1ysis ofthe reflected light intensity is used to determine the enhancement factor. It allows for an easy in-situ monitoring ofthe enhancement during atom reflection experiments. This waveguide structure was used to reflect rubidium atoms with a spontaneous emission probability below 1 %
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Submitted on : Wednesday, April 1, 2009 - 12:18:44 PM
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  • HAL Id : tel-00372495, version 1

Citation

Guillaume Labeyrie. Deux outils pour l'optique atomique : Jet intense d'hélium métastable et Miroir à onde évanescente exaltée. Physique Atomique [physics.atom-ph]. Université Paris Sud - Paris XI, 1998. Français. ⟨tel-00372495⟩

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