We present a cold atom gravimeter dedicated to field applications. Despite the compactness of our gravimeter, we obtain performances (sensitivity 42 µGal/Hz 1/2 , accuracy 25 µGal) close to the best gravimeters. We report gravity measurements in an elevator which led us to the determination of the Earth's gravity gradient with a precision of 4 E. These measurements in a non-laboratory environment demonstrate that our technology of gravimeter is enough compact, reliable and robust for field applications. Finally, we report gravity measurements in a moving elevator which open the way to absolute gravity measurements in an aircraft or a boat.Cold atom interferometer is a promising technology to obtain a highly sensitive and accurate absolute gravimeter. Laboratory instruments [1][2][3] have already reached the performances of the best classical absolute gravimeters [4] with a sensitivity of ∼ 10 µGal/Hz 1/2 (1 µGal = 10 −8 m/s 2 ) and an accuracy of 5 µGal. Moreover, compared to classical absolute gravimeters, atom gravimeters can achieve higher repetition rate [5] and do not have movable mechanical parts. These qualities make cold atom gravimeters more adapted to onboard applications like gravity measurements in a boat or in a plane. Cold atom gravimeters could thus be very useful in geophysics [6] or navigation [7]. In this context, cold atom sensors start to be tested on mobile platforms. An atom accelerometer has been operated in a 0 g plane [8]. An atom gradiometer has also been tested in a slow moving truck [9]. In this article, we present a compact cold atom gravimeter dedicated to field applications. First, we describe our apparatus and the technologies that we use to have a compact and reliable instrument. Then, we present the performances of the gravimeter in a laboratory environment. Finally, we report gravity measurements in a static and in a moving elevator.The principle of our cold atom gravimeter is well described in the literature [1] and we summarize in this letter only the basic elements. In an atom gravimeter, the test mass is a gas of cold atoms which is obtained by laser cooling and trapping techniques [10]. This cloud of cold atoms is released from the trap and its acceleration is measured by an atom interferometry technique. We use a Mach-Zehnder type atom interferometer consisting in a sequence of three equally spaced Raman laser pulses which drive stimulated Raman transitions between two stable states of the atoms. In the end, the proportion of atoms in the two stable states depends sinusoidally on *

We propose a concept for future space gravity missions using cold atom interferometers for measuring the diagonal elements of the gravity gradient tensor and the spacecraft angular velocity. The aim is to achieve better performance than previous space gravity missions due to a very low white noise spectral behavior and a very high common mode rejection, with the ultimate goals of determining the fine structures of the gravity field with higher accuracy than GOCE and detecting time-variable signals in the gravity field better than GRACE.

Abstract. We describe the operation of a light pulse interferometer using cold 87 Rb atoms in reduced gravity. Using a series of two Raman transitions induced by light pulses, we have obtained Ramsey fringes in the low gravity environment achieved during parabolic flights. With our compact apparatus, we have operated in a regime which is not accessible on ground. In the much lower gravity environment and lower vibration level of a satellite, our cold atom interferometer could measure accelerations with a sensitivity orders of magnitude better than the best ground based accelerometers and close to proven spaced-based ones. PACS. PACS-key discribing text of that key -PACS-key discribing text of that keyAtom interferometry is one of the most promising candidates for ultra-accurate measurements of gravito-inertial forces [1], with both fundamental [2,3,4,5] and practical (navigation or geodesy) applications. Atom interferometry is most often performed by applying successive coherent beam-splitting and -recombining processes separated by an interrogation time T to a set of particles [6]. Understanding matter waves interferences phenomena follows from the analogy with optical interferometry [7,8]: the incoming wave is separated into two wavepackets by a first beam-splitter; each wave then propagates during a time T along a different path and accumulates a different phase; the two wavepackets are finally recombined by a last beam-splitter. To observe the interferences, one measures the two output-channels complementary probability amplitudes which are sine functions of the accumulated phase difference ∆φ. This phase difference increases with the paths length, i.e. with the time T between the beamsplitting pulses.When used as inertial sensors [9,10], the atoms are usually left free to evolve during the interrogation time T so that the interferometer is only sensitive to gravitoinertial effects. In particular, one avoids residual trapping fields that would induce inhomogeneities or fluctuations and would affect the atomic signal. The interrogation time T is consequently limited by, on the one hand, the free expansion of the atomic cloud, and, on the other hand, the free fall of the atomic cloud. The limitation of expansion is alleviated by the use of ultracold gases [11,12], Send offprint requests to: Fig. 1. Top: The atom interferometer assembled in the Airbus. The main rack on the left houses the laser sources and the control electronics. The rack on the front right contains the uninterruptable power-supply, the electrical panel and the high-power laser part. The rack on the back right hosts atomoptics part of the experiment. Bottom: the architecture of the atom interferometer.

The use of Raman laser generated by modulation for light-pulse atom interferometer allows to have a laser system more compact and robust. However, the additional laser frequencies generated can perturb the atom interferometer. In this article, we present a precise calculation of the phase shift induced by the additional laser frequencies. The model is validated by comparison with experimental measurements on an atom gravimeter. The uncertainty of the phase shift determination limits the accuracy of our compact gravimeter at 8 × 10 −8 m/s 2 . We show that it is possible to reduce considerably this inaccuracy with a better control of experimental parameters or with particular interferometer configurations.

We describe a simple Zeeman slower design using permanent magnets. Contrary to common wire-wound setups no electric power and water cooling are required. In addition, the whole system can be assembled and disassembled at will. The magnetic field is however transverse to the atomic motion and an extra repumper laser is necessary. A Halbach configuration of the magnets produces a high quality magnetic field and no further adjustment is needed. After optimization of the laser parameters, the apparatus produces an intense beam of slow and cold 87 Rb atoms. With typical fluxes of 1 to 5 × 10 10 atoms/s at 30 m · s −1 , our apparatus efficiently loads a large magneto-optical trap with more than 10 10 atoms in one second, which is an ideal starting point for degenerate quantum gases experiments.