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arXiv:1810.06042 · Physical Review A

Proof-of-principle demonstration of vertical-gravity-gradient measurement using a single-proof-mass double-loop atom interferometer

Isadora Perrin, Yannick Bidel, Nassim Zahzam, C. Blanchard, Alexandre Bresson, Malo Cadoret

Published Jan 2, 2019• 22 citations
arXivHTMLPDF

Abstract

We demonstrate a proof-of-principle of direct Earth gravity-gradient measurement with an atom interferometer-based gravity gradiometer using a single proof mass of cold $^{87}\mathrm{Rb}$ atoms. The atomic gradiometer is implemented in the so-called double-loop configuration, hence providing a direct gravity-gradient dependent phase shift insensitive to dc acceleration and constant rotation rate. The atom interferometer (AI) can be either operated as a gravimeter or a gradiometer by simply adding an extra Raman $\ensuremath{\pi}$ pulse. We demonstrate gravity-gradient measurements first using a vibration isolation platform and second without seismic isolation using the correlation between the AI signal and the vibration signal measured by an auxilliary classical accelerometer allowing one to bypass the absence of common-mode vibration noise rejection in a double-loop geometry. The simplicity of the experimental setup (a single atomic source and unique detection) and the immunity of the AI to rotation-induced contrast loss make it a possible candidate for onboard gravity-gradient measurements.

DOI
10.1103/physreva.99.013601

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Quantum interferometer gravity gradiometer for 3D mapping is a project for developing the technology of atom interferometer-based gravity sensor in space. The atom interferometer utilizes atomic particles as free fall test masses to measure inertial forces with unprecedented sensitivity and precision. It also allows measurements of the gravity gradient tensor components for 3D mapping of subsurface mass distribution. The overall approach is based on recent advances of laser cooling and manipulation of atoms in atomic and optical physics. Atom interferometers have been demonstrated in research laboratories for gravity and gravity gradient measurements. In this approach, atoms are first laser cooled to micro-kelvin temperatures. Then they are allowed to freefall in vacuum as true drag-free test masses. During the free fall, a sequence of laser pulses is used to split and recombine the atom waves to realize the interferometric measurements. We have demonstrated atom interferometer operation in the Phase I period, and we are implementing the second generation for a complete gradiometer demonstration unit in the laboratory. Along with this development, we are developing technologies at component levels that will be more suited for realization of a space instrument. We will present an update of these developments and discuss the future directions of the quantum gravity gradiometer project.
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