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.

Measuring gravity from an aircraft or a ship is essential in geodesy, geophysics, mineral and hydrocarbon exploration, and navigation. Today, only relative sensors are available for onboard gravimetry. This is a major drawback because of the calibration and drift estimation procedures which lead to important operational constraints. Atom interferometry is a promising technology to obtain onboard absolute gravimeter. But, despite high performances obtained in static condition, no precise measurements were reported in dynamic. Here, we present absolute gravity measurements from a ship with a sensor based on atom interferometry. Despite rough sea conditions, we obtained precision below 10−5 m s−2. The atom gravimeter was also compared with a commercial spring gravimeter and showed better performances. This demonstration opens the way to the next generation of inertial sensors (accelerometer, gyroscope) based on atom interferometry which should provide high-precision absolute measurements from a moving platform.

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