Muquans validates its quantum gravimeter

Quentum technologies are being put to the acid test : the absolute quantum gravimetre (AQG) of the start-up Muquans, which can measure very accurately gravitational acceleration and thereby determine the changes in subsurface masses, has passed its tests successfully. Till now, this kind of instrument, based on matter wave interferometry, was confined to the laboratory in the form of exceedingly complex instrumentation. A campaign of measurements carried out with a team of geophysicists, has shown that the Muquans AQG, the first industrial version of a matter vave gravimetre, could combine high performance and solidity with a capacity to function autonomously over periods of several weeks. It was possible to effectuate this demonstration thanks to a close collaboration between the start-up and scientists from the Monpelier Geosciences laboratory [1] and the Toulouse environmental Geosciences laboratory [2], within the framework of the Infrastructure de Recherche RESIF. These results [3] are the fruit of advanced research carried out for many years by the teams of two CNRS research directors [4] and their involvement in the creation of to advanced technology start-ups Muquans [5].

Until the emergence of quantum technologies, the best technique of absolute gravimetry was to measure using laser interferometry the acceleration of a corner cube reflector in free fall. The absolute quantum gravimeter is based on the principle of a measurement under free fall, but this involving the fall of a very low temperature cloud of atoms. Laser confined rubidium atoms are cooled to a temperature close to absolute zero. Under free fall, their vertical acceleration is then measured interferometically, which enables one to determine the gravitational acceleration to an accuracy one billion times better than the value of 9,80 m/s2.

The two parts of the instrument – the head of the detector and the electronic sensing device - were designed to be easily transportable, to adapt themselves to the conditions of the terrain (vibrations...), and to be set up easily thanks to software which makes the apparatus completely automatic. « A new, still more compact and robust, version of the instrument is being prepared for 2019 and will enable us to target the industrial and geophysics communities », notes Bruno Desruelle, president of Muquans.

These first results open the way to scientific and industrial perspectives, and in particular in the domain of geophysics applied to the internal structure of the Earth and its natural resources, for the surveillance of reservoirs and even for metrology.