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Free space atom-interferometry traditionally suffers from the large distances that atoms have to fall in order to achieve long interaction times. Trapped atom interferometry is emerging as a powerful way of achieving long interaction times in a reduced experimental volume. Here, we demonstrate bi-chromatic adiabatic magnetic shell traps as a novel tool for matterwave interferometry. We dress the magnetic hyperfine states of the F = 1 and F = 2 Rubidium 87 Bose-Einstein Condensates thus creating two independently controllable shell traps of which we use the F = 1 , m ¯ F = − 1 〉 and F = 2 , m ¯ F = 1 〉 adiabatic states. Using microwave pulses, we put atoms originally loaded into one of the two shell-traps into a superposition between the two shell traps. Since the two traps can be manipulated independently, their position and vertical curvature can be matched, thus creating a good starting point for an atom interferometer. This interferometer can be sensitive to spatially varying electric or magnetic fields, which could be DC or RF magnetic fields or microwaves. We demonstrate that the trap-matching afforded by the independent control of the shell traps allows for a tenfold increase in coherence times when compared to adiabatic potentials created by a single RF-frequency. For large-radius shells the atoms are confined to a 2D surface enabling highly sensitive imaging matterwave interferometers.

Both GRACE and GOCE have proven to be very successful missions, providing a wealth of data which are exploited for geophysical studies such as climate changes, hydrology, sea level changes, solid Earth phenomena, with benefits for society and the whole world population. It is indispensable to continue monitoring gravity and its changes from space, so much so that a GRACE follow-on mission has been launched in 2018. In this paper, a new satellite mission concept named MOCASS is presented, which can be considered as a GOCE follow-on, based on an innovative gradiometer exploiting ultra-cold atom technology and aimed at monitoring Earth mass distribution and its variations in time. The technical aspects regarding the payload will be described, illustrating the measurement principle and the technological characteristics of a cold atom interferometer that can measure gravity gradients. The results of numerical simulations will be presented for a one-arm and a two-arm gradiometer and for different orbit configurations, showing that an improvement with respect to GOCE could be obtained in the estimate of the static gravity field over all the harmonic spectrum (with an expected error of the order of 1 mGal at degree 300 for a 5-year mission) and that estimates are promising also for the time-variable gravity field (although GRACE is still performing better at very low degrees). Finally, the progress achievable by exploiting MOCASS observations for the detection and monitoring of geophysical phenomena will be discussed: the results of simulations of key geophysical themes (such as mass changes due to hydrology, glaciers and tectonic effects) with expected gravity change-rates, time constants and corresponding wavelengths, show that an improvement is attainable and that signals invisible to past satellites could be detected by exploiting the cold atom technology.

Satellite missions providing data for a continuous monitoring of the Earth gravity field and its changes are fundamental to study climate changes, hydrology, sea level changes, and solid Earth phenomena. GRACE-FO (Gravity Recovery and Climate Experiment Follow-On) mission was launched in 2018 and NGGM (Next Generation Gravity Mission) studies are ongoing for the long-term monitoring of the time-variable gravity field. In recent years, an innovative mission concept for gravity measurements has also emerged, exploiting a spaceborne gravity gradio-meter based on cold atom interferometers. In particular, a team of researchers from Italian universities and research institutions has proposed a mission concept called MOCASS (Mass Observation with Cold Atom Sensors in Space) and conducted the study to investigate the performance of a cold atom gradiometer on board a low Earth orbiter and its impact on the modeling of different geophysical phenomena. This paper presents the analysis of the gravity gradient data attainable by such a mission. Firstly, the mathematical model for the MOCASS data processing will be described. Then numerical simulations will be presented, considering different satellite orbital altitudes, pointing modes and instrument configurations (single-arm and double-arm); overall, data were simulated for twenty different observation scenarios. Finally, the simulation results will be illustrated, showing the applicability of the proposed concept and the improvement in modeling the static gravity field with respect to GOCE (Gravity Field and Steady-State Ocean Circulation Explorer).

Interplanetary missions have typically relied on Radio Science (RS) to recover gravity fields by detecting their signatures on the spacecraft trajectory. The weak gravitational fields of small bodies, coupled with the prominent influence of confounding accelerations, hinder the efficacy of this method. Meanwhile, quantum sensors based on Cold Atom Interferometry (CAI) have demonstrated absolute measurements with inherent stability and repeatability, reaching the utmost accuracy in microgravity. This work addresses the potential of CAI-based Gradiometry (CG) as a means to strengthen the RS gravity experiment for small-body missions. Phobos represents an ideal science case as astronomic observations and recent flybys have conferred enough information to define a robust orbiting strategy, whilst promoting studies linking its geodetic observables to its origin. A covariance analysis was adopted to evaluate the contribution of RS and CG in the gravity field solution, for a coupled Phobos-spacecraft state estimation incorporating one week of data. The favourable observational geometry and the small characteristic period of the gravity signal add to the competitiveness of Doppler observables. Provided that empirical accelerations can be modelled below the nm/s2 level, RS is able to infer the 6 × 6 spherical harmonic spectrum to an accuracy of 0.1–1% with respect to the homogeneous interior values. If this correlates to a density anomaly beneath the Stickney crater, RS would suffice to constrain Phobos’ origin. Yet, in event of a rubble pile or icy moon interior (or a combination thereof) CG remains imperative, enabling an accuracy below 0.1% for most of the 10 × 10 spectrum. Nevertheless, technological advancements will be needed to alleviate the current logistical challenges associated with CG operation. This work also reflects on the sensitivity of the candidate orbits with regard to dynamical model uncertainties, which are common in small-body environments. This brings confidence in the applicability of the identified geodetic estimation strategy for missions targeting other moons, particularly those of the giant planets, which are targets for robotic exploration in the coming decades.

Atom-interferometry gravity gradiometry has been developed as a promising technique for future gravity gradiometric missions after GOCE due to its greater sensitivity in micro-gravity environments and constant performance over the measurement bandwidth. In this paper, a feasible method of spaceborne atom-interferometry gravity gradiometry is proposed by utilizing the free-fall condition of the cold atoms in space. Compared with GOCE, which shows an in-orbit noise performance of 10~20 mE/Hz1/2, the scheme described in this paper would achieve a high sensitivity of 1.9 mE/Hz1/2 for gravity gradients measurement by reducing the orbital altitude and optimizing the interrogation time for atom interferometry. The results show that the proposed scheme could significantly augment the spectral content of the gravity field in the degree and order of 280~316 and resolve the global gravity field with an improved accuracy of 0.2 cm@100 km and 0.85 cm@80 km in terms of geoid height, and 0.06 mGal@100 km and 0.3 mGal@80 km in terms of gravity anomaly after 1270 days of data collection.

Errors and uncertainties in${\\lambda }_{\\mathrm{zero}}$calculations presented by Chamakhi et al (2015 New J. Phys. http://dx.doi.org/10.1088/1367-2630/17/12/123002 17 http://dx.doi.org/10.1088/1367-2630/17/12/123002 ) are identified.

We developed a gravity-gradiometer based on atom interferometry for the determination of the Newtonian gravitational constant G. The apparatus, combining a Rb fountain, Raman interferometry and a juggling scheme for fast launch of two atomic clouds, was specifically designed to reduce possible systematic effects. We present instrument performances and preliminary results for the measurement of G with a relative uncertainty of 1%. A discussion of projected accuracy for G measurement using this new scheme shows that the results of the experiment will be significant to discriminate between previous inconsistent values.

The extreme miniaturization of a cold-atom interferometer accelerometer requires the development of novel technologies and architectures for the interferometer subsystems. Here, we describe several component technologies and a laser system architecture to enable a path to such miniaturization. We developed a custom, compact titanium vacuum package containing a microfabricated grating chip for a tetrahedral grating magneto-optical trap (GMOT) using a single cooling beam. In addition, we designed a multi-channel photonic-integrated-circuit-compatible laser system implemented with a single seed laser and single sideband modulators in a time-multiplexed manner, reducing the number of optical channels connected to the sensor head. In a compact sensor head containing the vacuum package, sub-Doppler cooling in the GMOT produces 15 μK temperatures, and the GMOT can operate at a 20 Hz data rate. We validated the atomic coherence with Ramsey interferometry using microwave spectroscopy, then demonstrated a light-pulse atom interferometer in a gravimeter configuration for a 10 Hz measurement data rate and T  = 0–4.5 ms interrogation time, resulting in Δ g / g  = 2.0 × 10 −6 . This work represents a significant step towards deployable cold-atom inertial sensors under large amplitude motional dynamics. Cold-atom interferometers have been miniaturized towards fieldable quantum inertial sensing applications. Here the authors demonstrate a compact cold-atom interferometer using microfabricated gratings and discuss the possible use of photonic integrated circuits for laser systems.

Using an atom interferometer, we have measured the static electric polarizability of 7Li α=(24.33 ±0.16)×10-30 m3 = 164.2±1.1 atomic units with a 0.66% uncertainty. Our experiment, which is similar to an experiment done on sodium in 1995 by Pritchard and co-workers, consists in applying an electric field on one of the two interfering beams and measuring the resulting phase-shift. With respect to Pritchard's experiment, we have made several improvements which are described in detail in this paper: the capacitor design is such that the electric field can be calculated analytically; the phase sensitivity of our interferometer is substantially better, near 16 mrad/\\(Hz\\); finally our interferometer is species selective so that impurities present in our atomic beam (other alkali atoms or lithium dimers) do not perturb our measurement. The extreme sensitivity of atom interferometry is well illustrated by our experiment: our measurement amounts to measuring a slight increase Δv of the atom velocity v when it enters the electric field region and our present sensitivity is sufficient to detect a variation Δv/v ≈6 ×10-13.

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. Measuring gravitational and inertial acceleration in a moving platform is important for sensing and navigation but is also very challenging. Here the authors demonstrate the ship-borne absolute gravity acceleration measurements using an atom interferometer.