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Gravimétrie atomique, amélioration de l'exactitude et nouvelles géométries

Abstract : The goal of the absolute gravimeter is to measure the gravitational accelration with a relative accuracy of 10-9 for the metrological "watt balance" project. During my thesis, we developped a new vaccum chamber, which allowed us to evaluate the limiting systematic errors. The gravimeter was made transportable and was installed close to the LNE watt balance. The gravimeter uses atom interferometry, where a cold cloud of 87Rb atoms in free fall is manipulated thanks to two-photon transitions. We reduced the measurement uncertainty below the goal, except for laser wavefront aberation effects. This is currently under investigations and we aim for perfect control of the atomic trajectories. During the year 2010, our atomic gravimeter participated in international "Key" comparisons. The results we obtained are in agreement with other gravimeters, but we observed some fluctuations in the differences with other gravimeters, caused by variations of the wavefront aberration effects. In parallel, we developed three new methods of atom interferometry measurement. The first method uses a three-point algorithm which makes the measurement robust from vibrations. The second consists in diffracting atoms simultaneously by the four fields present in the chamber, in order to double the area of the interferometer, and thus increases its intrinsic sensitivity. Last, we designed and characterized a hollow pyramid, which allows the differents lasers to be replaced by a single laser beam, in order to create a compact transportable atomic gravimeter.
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https://tel.archives-ouvertes.fr/tel-00552301
Contributor : Quentin Bodart <>
Submitted on : Friday, July 22, 2011 - 5:00:36 PM
Last modification on : Monday, December 14, 2020 - 9:55:12 AM
Long-term archiving on: : Friday, November 4, 2011 - 3:12:01 PM

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  • HAL Id : tel-00552301, version 2

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Quentin Bodart. Gravimétrie atomique, amélioration de l'exactitude et nouvelles géométries. Physique Atomique [physics.atom-ph]. Université Pierre et Marie Curie - Paris VI, 2010. Français. ⟨tel-00552301v2⟩

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