First evaluation of an absolute quantum gravimeter (AQG#B01) for future field experiments

Quantum gravimeters are a promising new development allowing for continuous absolute gravity monitoring while<br> remaining user-friendly and transportable. In this study, we present experiments carried out to assess the capacity of the<br> AQG#B01 in view of future deployment as a field gravimeter for hydro-geophysical applications. The AQG#B01 is the field<br> version follow-up of the AQG#A01 portable absolute quantum gravimeter developed by the French quantum sensor company<br> Muquans. We assess the instrument’s performance in terms of stability (absence of instrumental drift), sensitivity in relation to<br> other gravimeters. Furthermore, the measurements allowed for the successful monitoring of a hydrological mass change. We<br> discuss the observations concerning the accuracy of the AQG#B01 in comparison with a state-of-the-art absolute gravimeter<br> (Micro-g-LaCoste, FG5#228). Repeatability is tested by instrument displacement between close-by measurement positions.<br> We report the repeatability to be better than 50 nm.s−2 . No significant instrumental drift was observed over several weeks<br> of measurement. This study furthermore investigates whether changes of instrument tilt and external temperature and com-<br> bination of both, which are likely to occur during field campaigns, influence the measurement of gravitational attraction. We<br> ◦repeatedly tested external temperatures between 20 and 30 C and did not find any significant effect. We report two weeks<br> of stable operation under semi-terrain conditions in a garage without temperature-control. As an example of a geophysical<br> signal, a 100 nm.s−2 gravity change is detected with the AQG#B01 after a rainfall event at the Larzac geodetic observatory<br> (Southern France). The data agreed with the gravity changes measured with a superconducting relative gravimeter (GWR,<br> iGrav#002) and the expected gravity change simulated as an infinite Bouguer slab approximation. We close with operational<br> recommendations for potential users and discuss specific possible future field applications. While not claiming completeness,<br> we nevertheless present the first characterisation of a quantum gravimeter carried out by future users. Crucial criteria for the<br> assessment of its suitability in field applications have been investigated and are complemented with a discussion of further<br> necessary experiments.