Compact differential gravimeter at the quantum projection-noise limit
Camille Janvier, Vincent Ménoret, Bruno Desruelle, Sébastien Merlet, Arnaud Landragin, Franck Pereira dos Santos
Abstract
Atom interferometry offers new perspectives for geophysics and inertial sensing. We present the industrial prototype of a 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 ${\mathrm{\ensuremath{\Gamma}}}_{zz}$. While the sensitivity to $g$ is competitive with the best industrial gravimeters, the sensitivity on ${\mathrm{\ensuremath{\Gamma}}}_{zz}$ reaches the limit set by quantum projection noise---leading to a long-term stability of $0.1\phantom{\rule{0.28em}{0ex}}\mathrm{E}$ ($1\phantom{\rule{0.28em}{0ex}}\mathrm{E}=1\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}9}\phantom{\rule{0.28em}{0ex}}{\mathrm{s}}^{\ensuremath{-}2}$). This dual-purpose instrument constitutes the industrial integration of cold atom sensors for practical applications. It paves the way for different applications in geophysics, civil engineering, and gravity-aided navigation, where accurate mapping of the gravitational field plays an important role.