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Free fall atom interferometers
9 October 2022
The atom interferometers that we are developing are based on the use of laser beam splitters, which allow to split and recombine atomic wave packets in a coherent way. Our experiments use free falling laser cooled atoms, or ultracold atoms produced by evaporative cooling, as probes of inertial fields, and light beamsplitters based on stimulated Raman transitions or Bragg diffraction. The use of cold atoms enable longer interaction times leading to a higher sensitivity to the inertial forces. Their accuracy surpasses these of standard technology sensors. Undergoing studies will lead to unprecedent performances, opening the way for tests of fundamental physics (relativity, standard model or detection of gravitational waves).
| Atom interferometry techniques lead to the measurement of the Earth’s gravity at the level of the state of the art. The absolute gravimeter is developed in the frame of the watt balance project of the Laboratoire National de Métrologie et d’Essais (LNE). The goal of this experiment is to measure gravity acceleration with a relative accuracy better than 1 ppb. The short-term performances of the interferometer are already at the level of the state of the art. Ongoing modifications will allow to reach the target accuracy and to test the possible benefits from the use of ultra-cold atoms to this kind of sensor. |
| With the developement of the first cold atom gyroscope, we have demonstrated the ability to measure all axes of inertia (three components of acceleration and the three components of rotations) within the same apparatus and performances at the level of the standard technologies (optical gyroscopes and mechanical accelerometers). The new experiment of a large area gyroscope allowed reaching an unprecedented level of stability, opening the way to new possibilities of testing fundamental physics. |
| The coherent interferometry experiment for space (ICE) aims at testing the weak equivalence principle by looking to the equivalence of free fall of different bodies in the zero-g CNES plane. The experiment consists in a double interferometer using two different atomic species simultaneously. This experiment is a common development with the LP2N de l’Institut d’Optique d’Aquitaine (Philippe Bouyer). For more information, please contact A. Landragin. Theses studies contribute to the preparation of the mission STE-QUEST, in which the team is highly involved. |
| The project MIGA has been selected as EQUIPEX in December 2011. This equipment will enable to study with a new approach fluctuations of gravity and strains due to gravitational waves. The measurements will be realized in the frequency range from Hz to mHz and with unprecedented precision. It concerns in the same time geophysics and test of fundamental physics applications. This equipment is based on largely spaced atom interferometers (250 m) and which are coupled together by lasers used as atomic beam splitters and which are resonant within a large optical cavity. |
| The atomic gradiometer project aims to achieve unmatched performances for the measurement sensitivity of the gravity gradient, through the use of ultra-cold atoms and large momentum transfer beamsplitters. The principle of its differential measurement, which eliminates the deleterious impact of vibration noise, makes it an ideal platform for demonstrating these new methods. It is also a sensor of choice for on-board gravity measurements, on various carriers, and in particular from orbiting satellites, for the global measurement of the Earth’s gravity field. |