The first commercial, compact and transportable quantum gravimeter was used in a series of measurement campaigns lasting several days by a team of geophysicists. The instrument, which has thus demonstrated its ability to combine high performance and reliability, is marketed by the start-up Muquans, founded in association with researchers from the CNRS, the Institut d’optique Graduate School and the Paris Observatory as part of Résif.

Quantum technologies are putting themselves to the test in the field: the absolute quantum gravimeter (AQG) from the start-up company Muquans, which enables the acceleration of gravity to be measured with great precision and thus to evaluate changes in mass below the surface of the earth, has successfully passed its release. Until now, such instruments, based on a matter-wave interferometer, have remained confined to the laboratory as highly complex experimental devices. A campaign of measurements carried out with geophysicists showed that the Muquans GQA, the first industrial version of a matter-wave gravimeter, could combine high performance and robustness with autonomous operation over a period of several weeks. This demonstration was made possible thanks to a close collaboration between the start-up and researchers from the Geosciences Montpellier laboratories [1] and Environmental Geosciences Toulouse [2], within the framework of the Reactive Research infrastructure [3]. All of these results [4] is the result of high-level research work carried out over several years by the teams of two CNRS research directors [5] and their involvement in the creation of the high-tech company Muquans. [6].

Until the advent of quantum technologies, the best method of absolute gravimetry was to measure by laser interferometry the acceleration experienced by a free-falling cube corner reflector. The absolute quantum gravimeter is based on the principle of a free-fall measurement, but this time characterizing the fall of a cloud of atoms at very low temperatures. Rubidium atoms, trapped by lasers, are cooled to a temperature close to absolute zero. Left in free fall, their vertical acceleration is then measured by an interferometric device, which makes it possible to evaluate the acceleration of gravity with an uncertainty 1 billion times smaller than the value of 9.80 m/s².

The two parts of the instrument – the sensor head and the electronic control device – have been developed to be easily transportable, to be adapted to field conditions (vibrations…), and to be easily implemented thanks to a software that allows a fully automatic operation of the instrument. “A new version of the instrument, even more compact and robust, is being prepared for 2019 and will enable us to attack the industrial geophysics market,” says Bruno Desruelle, President of Muquans.

These initial results open up broad prospects for scientific and industrial applications, particularly in the field of geophysics, the study of the internal structure of the globe and natural resources, the monitoring of reservoirs and metrology.


Bruno Desruelle / President of Muquans /

[1] Geosciences Laboratory (CNRS/University of Montpellier/University of the West Indies)
[2] Environmental Geosciences Laboratory Toulouse (CNRS/Université Paul Sabatier/IRD/CNES)
[3] Résif : French Seismological and Geodetic Network. Résif-Core is an Equipment of Excellence supported by the Investment for the Future Program to provide France with equipment of excellence for the observation and understanding of the internal Earth.
[4] Gravity measurements below 10-9 g with a transportable absolute quantum gravimeter. Vincent Méronet, Pierre Vermeulen, Nicolas Le Moigne, Sylvain Bonvalot, Phillipe Bouyer, Arnaud Landragin and Bruno Desruelle. Nature Scientific Reports, 2018, 8:12300 | DOI : 10.1038/s41598-018-30608-1
[5] Phillipe Bouyer, Director of the Photonics, Digital and Nanosciences Laboratory (CNRS/Institut d’optique graduate school/University of Bordeaux) and Arnaud Landragin, Director of the Time-Space Reference Systems Laboratory (CNRS/Observatoire de Paris/Sorbonne University).
[6] Muquans employs 25 people and also markets an atomic clock, laser systems and optical repeaters (used for frequency transfer over a fibre link as part of the Refimeve project).


Absolute Quantum Gravimeter Muquans