Inertial sensors relying on atom interferometry offer a breakthrough advance in a variety of applications, such as inertial navigation, gravimetry or ground- and space-based tests of fundamental physics. These instruments require a quiet environment to reach their performance and using them outside the laboratory remains a challenge. Here we report the first operation of an airborne matter-wave accelerometer set up aboard a 0g plane and operating during the standard gravity (1g) and microgravity (0g) phases of the flight. At 1g, the sensor can detect inertial effects more than 300 times weaker than the typical acceleration fluctuations of the aircraft. We describe the improvement of the interferometer sensitivity in 0g, which reaches 2 x 10-4 ms-2 / √Hz with our current setup. We finally discuss the extension of our method to airborne and spaceborne tests of the Universality of free fall with matter waves.

The theory of general relativity describes macroscopic phenomena driven by the influence of gravity while quantum mechanics brilliantly accounts for microscopic effects. Despite their tremendous individual success, a complete unification of fundamental interactions is missing and remains one of the most challenging and important quests in modern theoretical physics. The STE-QUEST satellite mission, proposed as a medium-size mission within the Cosmic Vision program of the European Space Agency (ESA), aims for testing general relativity with high precision in two experiments by performing a measurement of the gravitational redshift of the Sun and the Moon by comparing terrestrial clocks, and by performing a test of the Universality of Free Fall of matter waves in the gravitational field of Earth comparing the trajectory of two Bose-Einstein condensates of 85 Rb and 87 Rb. The two ultracold atom clouds are monitored very precisely thanks to techniques of atom interferometry. This allows to reach down to an uncertainty in the Eötvös parameter of at least 2 · 10 −15 . In this paper, we report about the results of the phase A mission study of the atom interferometer instrument covering the description of the main payload elements, the atomic source concept, and the systematic error sources.

We report the realization of a matter-wave interferometer based on Raman transitions which simultaneously interrogates two different atomic species ( 87 Rb and 85 Rb). The simultaneous aspect of our experiment presents encouraging preliminary results for future dual-species atom interferometry projects and seems very promising by taking advantage of a differential acceleration measurement. Indeed the resolution of our differential accelerometer remains lower than 3.9 × 10 −8 g even with vibration levels up to 1 × 10 −3 g thanks to common-mode vibration noise rejection . An atom based test of the Weak Equivalence Principle has also been carried out leading to a differential free fall measurement between both isotopes of ∆g/g = (1.2 ± 3.2) × 10 −7 .Light pulse atom interferometers [1, 2] have proven to be very high performance sensors with the development in the last decades of cold atom gravimeters [3], gravity gradiometers [4] and gyroscopes [5]. In addition to the undeniable contribution they could bring in practical applications such as inertial navigation and geophysics, they appear very promising for exploring fundamental physics such as for the determination of the fine structure constant [6], the gravitationnal constant [7,8], but also for testing the Einstein's theory of general relativity with quantum objects [9]. In that field, atom interferometers seem notably promising for detecting gravitational waves [10], exploring short range forces [11,12] and testing the Weak Equivalence Principle (WEP) [13].In the context of testing the WEP, some projects under development aim to measure the acceleration of two different atomic species during few seconds of free fall in order to achieve highly sensitive measurements as it can be obtained in 10 m tall atomic fountains [9], drop towers [14], sounding rockets, parabolic flights [15] and satellites [16]. To date, a single atom based ground test of the WEP was carried out by alternatively handling both isotopes of rubidium [13]. This method, providing a non simultaneous differential measurement, exhibit a sensitivity limited by vibration noise, such as state of the art gravimeters [17,18]. A special interest must thus be paid to develop atom interferometers which will simultaneously interrogate two different atomic species in order to take full advantages of a differential measurement and to achieve the targeted sensitivity and accuracy.