G016-02
Optimization of a Differential Quantum Gravimeter

Monday, 14 December 2020: 17:34
Virtual
Bruno Desruelle1, Camille Janvier2, Vincent Menoret2, Jean Lautier-Gaud2, Sébastien Merlet3, Franck Pereira dos Santos3 and Arnaud Landragin3, (1)Muquans, Pessac, France, (2)Muquans, Talence, France, (3)LNE-SYRTE, Observatoire de Paris-Université PSL, CNRS, Sorbonne Université, Paris, France
Recorded Presentation
Abstract:
One year after the first signals were obtained on the Differential Quantum Gravimeter (DQG), we report on the optimization of the experimental performances. DQG is unique as it is an industry-grade geophysics-oriented instrument that simultaneously measures the local gravity acceleration and its vertical gradient. Relying on a similar physical principle and same technologies developed for our absolute quantum gravimeters (AQG) [1], a single vertical laser beam simultaneously measures the vertical acceleration experienced by two sets of laser-cooled atoms free-falling from different heights. The vertical acceleration gives a direct access to g, and the difference of both measurements yields dg/dz. [2,3].

Our demonstrator has been operational for a year and has been able to demonstrate sensitivity to the gradient of 60 E/√t (1E = 10-9 s-2 = 1 nm/s²/m), and 360 nm/s²/√t for g, on the third floor of a university building. Long term caracterisation of the stability is ongoing in order to reach 1 E and 10nm/s² on a long measurement. Performance of the dual tracking has been evaluated and compared to regular gravity tracking for each atom cloud. Using a tip-tilt retro-reflection mirror we also have been able to carefully measure and compensate for the Coriolis effect. Further measurements are underway to address accuracy for both signals.

This instrument opens new possibilities in the detection of underground density heterogeneities and promises to be a powerful tool for gravimeter comparisons.

This work has been supported by the DGA under contract 162906044.


[1] V. Ménoret et al., "Gravity measurements below 10−9 g with a transportable absolute quantum gravimeter", Nature Scientific Reports, vol. 8, 12300 (2018)
[2] M. J. Snadden et al. “Measurement of the Earth's Gravity Gradient with an Atom Interferometer-Based Gravity Gradiometer” , Phys. Rev. Lett. 81, 971 (1998)

[3] R. Caldani et al. "Simultaneous accurate determination of both gravity and its vertical gradient", Phys. Rev. A 99, 033601 (2019)

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