A Spaceborne Gravity Gradiometer Concept Based on Cold Atom Interferometers for Measuring Earth’s Gravity Field

Carraz, Olivier; Siemes, Christian; Massotti, Luca; Haagmans, Roger; Silvestrin, Pierluigi

doi:10.1007/s12217-014-9385-x

Cited by 94 publications

(88 citation statements)

References 30 publications

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“…There is an alternative expression for equation (25) as the overlap of two Wigner functions with a relative phase-space displacement χ δ (valid only for pure states): where the density matrices ρ and ρ χ δ correspond respectively to the states ψ…”

Section: Phase-space Descriptionmentioning

confidence: 99%

“…The potential of light-pulse atom interferometry [1,2] for high-precision measurements has been amply demonstrated with its successful implementation in extremely sensitive inertial sensors, including gyroscopes [3][4][5], gradiometers [6] and the currently most precise absolute gravimeters [7][8][9]. It has already found applications in accurate measurements of fundamental constants [10][11][12][13][14][15] and tests of fundamental properties [16][17][18], and it is a key ingredient in plans for future tests of the equivalence principle in space [19,20] (atom-interferometry-based experiments have already been performed on the ground [21][22][23][24]), next-generation satellite geodesy missions [25] or even alternative proposals for gravitational-wave detection [26]. Achieving higher sensitivities requires extended interferometer times (the phase shift generated by accelerations, for instance, grows with the square of the interferometer time).…”

Section: Introductionmentioning

confidence: 99%

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Overcoming loss of contrast in atom interferometry due to gravity gradients

2014

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Long-time atom interferometry is instrumental to various high-precision measurements of fundamental physical properties, including tests of the equivalence principle. Due to rotations and gravity gradients, the classical trajectories characterizing the motion of the wave packets for the two branches of the interferometer do not close in phase space, an effect which increases significantly with the interferometer time. The relative displacement between the interfering wave packets in such open interferometers leads to a fringe pattern in the density profile at each exit port and a loss of contrast in the oscillations of the integrated particle number as a function of the phase shift. Paying particular attention to gravity gradients, we present a simple mitigation strategy involving small changes in the timing of the laser pulses which is very easy to implement. A useful representation-free description of the state evolution in an atom interferometer is introduced and employed to analyze the loss of contrast and mitigation strategy in the general case. (As a by-product, a remarkably compact derivation of the phaseshift in a general light-pulse atom interferometer is provided.) Furthermore, exact results are obtained for (pure and mixed) Gaussian states which allow a simple interpretation in terms of the alignment of Wigner functions in phase-space. Analytical results are also obtained for expanding Bose-Einstein condensates within the time-dependent Thomas-Fermi approximation. Finally, a combined strategy for rotations and nonaligned gravity gradients is considered as well.

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Section: Phase-space Descriptionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Overcoming loss of contrast in atom interferometry due to gravity gradients

2014

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“…The space qualified technologies developed in the frame of this project are easily transposable to other wavelength and pave the way for future cold atom space missions including optical clocks 16 and atom interferometers 17,18 .…”

Section: Discussionmentioning

confidence: 99%

PHARAO laser source flight model: Design and performances

Lévèque

Faure

Esnault

et al. 2015

Review of Scientific Instruments

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In this paper, we describe the design and the main performances of the PHARAO laser source flight model. PHARAO is a laser cooled cesium clock specially designed for operation in space and the laser source is one of the main sub-systems. The flight model presented in this work is the first remote-controlled laser system designed for spaceborne cold atom manipulation. The main challenges arise from mechanical compatibility with space constraints, which impose a high level of compactness, a low electric power consumption, a wide range of operating temperature and a vacuum environment. We describe the main functions of the laser source and give an overview of the main technologies developed for this instrument. We present some results of the qualification process. The characteristics of the laser source flight model, and their impact on the clock performances, have been verified in operational conditions.

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“…Finally, the method proposed here, which relies on the use of ultracold atoms as a source, can be applied to any atomic sensor based on light beamsplitters, which are inevitably affected by distortions of the lasers wavefronts. The improved control of systematics it provides will have significant impact in high precision measurements with atom interferometry, with important applications to geodesy [39,40], fundamental physics tests [20,41,42] and to the development of highest grade inertial sensors [43].…”

Section: Prospectsmentioning

confidence: 99%

Improving the accuracy of atom interferometers with ultracold sources

et al. 2018

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We report on the implementation of ultracold atoms as a source in a state of the art atom gravimeter. We perform gravity measurements with 10nm s −2 statistical uncertainties in a so-far largely unexplored temperature range for such a high accuracy sensor, down to 50 nK. This allows for an improved characterization of the most limiting systematic effect, related to wavefront aberrations of light beamsplitters. A thorough model of the impact of this effect onto the measurement is developed and a method is proposed to correct for this bias based on the extrapolation of the measurements down to zero temperature. Finally, an uncertainty of 13 nm s −2 is obtained in the evaluation of this systematic effect, which can be improved further by performing measurements at even lower temperatures. Our results clearly demonstrate the benefit brought by ultracold atoms to the metrological study of free falling atom interferometers. By tackling their main limitation, the method presented here allows reaching record-breaking accuracies for inertial sensors based on atom interferometry.

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A Spaceborne Gravity Gradiometer Concept Based on Cold Atom Interferometers for Measuring Earth’s Gravity Field

Cited by 94 publications

References 30 publications

Overcoming loss of contrast in atom interferometry due to gravity gradients

Overcoming loss of contrast in atom interferometry due to gravity gradients

PHARAO laser source flight model: Design and performances

Improving the accuracy of atom interferometers with ultracold sources

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