Sensitivity limits of a Raman atom interferometer as a gravity gradiometer

TLDR

The study evaluates the sensitivity of a dual‑cloud atom interferometer for measuring vertical gravity gradients. The authors analyze how key experimental parameters affect noise and long‑term drifts in the interferometer. The interferometer achieves a short‑term sensitivity of 3×10⁻⁹ g/√Hz limited by quantum projection noise, reaches 5×10⁻¹¹ g after 8000 s with active control, and its long‑term stability permits a determination of G at the 10⁻⁴ level after about 100 h.

Abstract

We evaluate the sensitivity of a dual cloud atom interferometer to the measurement of vertical gravity gradient. We study the influence of most relevant experimental parameters on noise and long term drifts. Results are also applied to the case of doubly differential measurements of the gravitational signal from local source masses. We achieve a short-term sensitivity of $3\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}9}$ g/\sqrt{\text{Hz}}$ to differential gravity acceleration, limited by the quantum projection noise of the instrument. Active control of the most critical parameters allows us to reach a resolution of $5\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}11}$ g after 8000 s on the measurement of differential gravity acceleration. The long-term stability is compatible with a measurement of the gravitational constant $G$ at the level of ${10}^{\ensuremath{-}4}$ after an integration time of about 100 h.