A compact differential gravimeter at the quantum projection noise limit

Abstract

Atom interferometry offers new perspectives for geophysics and inertial sensing. We present the industrial prototype of a new type of quantum-based instrument: a compact, transportable, differential quantum gravimeter capable of measuring simultaneously the absolute values of both gravitational acceleration, g, and its vertical gradient, Γzz. While the sensitivity to g is competitive with the best industrial gravimeters, the sensitivity on Γzz reaches the limit set by quantum projection noise-leading to an unprecedented long-term stability of 0.1 E (1 E=1×10 −9 s −2 ). This unique, dual-purpose instrument, paves the way for new applications in geophysics, civil engineering, and gravity-aided navigation, where accurate mapping of the gravitational field plays an important role.

Position fixing with cold atom gravity gradiometers

“…We start by examining the ability of the proposed method to correct the position of the navigation solution where there is no phase noise, only shot noise. This provides a baseline case, and is motivated in part by recent work on systems that should be shot noise limited 21 . We then consider the effect of phase noise on the approach and the robustness to failed measurements, which could be due to vibrations or other inadvertent motion causing the cold atoms to move outside the Raman beam.…”

“…Cold atom gravity gradiometers consist of two atom interferometers separated by a known distance and sharing a common Raman laser reference signal [13][14][15][16][17][19][20][21] . Clouds of cold atoms are prepared and held in a magneto-optical trap inside a vacuum chamber.…”

“…Cold atom sensors offer unprecedented precision and accuracy in the measurement of inertial quantities [1][2][3][4][5][6][7][8] , including gravitational acceleration [9][10][11][12] and gravity gradients [13][14][15][16][17][19][20][21] . The accuracy of cold atom devices derives from a quantum mechanical property of atoms, the phase sensitivity of matter wave interferometry 22,23 , which can be several orders of magnitude (or more) better than optical interferometers, and the fact that the masses of all isotopically pure atoms are all identical, meaning that systematic biases in gravity measurement due to minute differences in mass are effectively zero.…”

Cold atom inertial sensors for navigation applications

“…Cold atom interferometers can be sensitive to accelerations [51] or rotations [9,52,53] or, more generally, both [3].…”