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Communication Dans Un Congrès Année : 2020

Quantum Absolute Sensors for Gravity Measurements

Résumé

Gravity measurements are performed with two different classes ofinstruments: gravimeters, most widely used, measure the gravityacceleration gand its variations, whereas gradiometers measure itsgradient.Quantum gravity sensors, based on cold atom interferometrytechniques, can offer higher sensitivities and accuracies than currentstate of the art commercial available technologies. Their limits inperformances, both in terms of accuracy and long term stability, arelinked to the temperature of the atomic cloud, in the low µK range, andmore specifically, to the residual ballistic expansion of the atomicsources in the laser beams. To overcome these limits, we use ultracoldatoms in the nano-kelvin range in our sensors.I will first present ourCold Atom Gravimeter (CAG) used for the determination of the Planckconstant with the LNE Kibble Balance [1]. It performs continuously 3gravity measurements per second with a demonstrated long term stabilityof 0.06 nano-gin 40 000 s of measurement. Using ultracold atoms producedby evaporative cooling in a crossed dipole trap as a source, itsaccuracy, which is still to be improved, is currently at the level of 2nano-g. This makes our CAG, the more accurate gravimeter [2]. It detectswater table level variations. Then I will describe a « dual sensor »which performs simultaneous measurements of g and its gradient. Thisoffers in principle the possibility to resolve, by combining these twosignals, the ambiguities in the determination of the positions andmasses of the sources, offering new perspectives for applications. Ituses cold atom sources for proof of principle demonstrations [3, 4] andwill soon combine ultra-cold atomic samples produced by magnetic trapson a chip and large momentum beamsplitters. With these two key elements,the gradiometer will perform measurements in the sub-E sensitivity rangein 1 s measurement time on the ground. Such a level of performancesopens new prospects for on field and on board gravity mapping, for driftcorrection of inertial measurement units in navigation, for geophysicsand for fundamental physics. References[1] M. Thomas et al. Metrologia54, 468-480 (2017)[2] R. Karcher, et al. New J. Phys. 20, 113041(2018)[3] M. Langlois et al. Phys. Rev. A 96, 053624 (2017)[4] R.Caldani et al. Phys. Rev. A 99, 033601 (2019)
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hal-03734308 , version 1 (21-07-2022)

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Sébastien Merlet, Raphael Piccon, Sumit Sarkar, Franck Pereira dos Santos. Quantum Absolute Sensors for Gravity Measurements. EGU General Assembly Conference Abstracts, May 2020, Vienna, Austria. pp.8392. ⟨hal-03734308⟩
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