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Développement de méthodes asymptotiques pour l'étude des interactions entre atomes froids ; détermination de longueurs de diffusion du sodium et du césium

Abstract : Precise knowledge of cold-atom collision properties is essential for the studies of Bose-Einstein condensation or cold molecule formation. In such experiments, the interaction mainly occurs at rather large interatomic distance, in the so-called asymptotic region. We have developed a purely asymptotic method which allows us to fully describe the collision properties of cold alkali atoms without using the inner part of the molecular potentials, which is often known with a poor precision. The key point of the method is the nodal lines, which are the lines connecting the nodes of successive radial wavefunctions near the ground state threshold. Within the framework of Born-Oppenheimer approximation, computing such nodal lines, by numerical integration of the radial Schrödinger equation in the asymptotic region only, provides a very simple way to derive scattering lengths from observed bound level positions. The method has been extended to the multichannel case and appears now as a genuine parametric method, in which a few parameters (some chosen nodal lines) replace the inner part of the potentials. These nodal lines are used as fitting parameters, which are ajusted on experimental results. Once these parameters have been determined, any collision property such as scattering lengths, clock shifts or magnetic field induced Feshbach resonances can be deduced in principle. This method has been applied to obtain the collision properties of ultracold sodium and cesium atoms.
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https://tel.archives-ouvertes.fr/tel-00011676
Contributor : Benoît t'Jampens <>
Submitted on : Friday, February 24, 2006 - 12:35:20 AM
Last modification on : Wednesday, October 14, 2020 - 4:00:21 AM
Long-term archiving on: : Saturday, April 3, 2010 - 10:33:56 PM

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  • HAL Id : tel-00011676, version 1

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Benoît t'Jampens. Développement de méthodes asymptotiques pour l'étude des interactions entre atomes froids ; détermination de longueurs de diffusion du sodium et du césium. Physique Atomique [physics.atom-ph]. Université Paris Sud - Paris XI, 2002. Français. ⟨tel-00011676⟩

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