Influence of noise on a magnetically sensitive atom interferometer
S. A. DeSavage, Arvind Srinivasan, Jon P. Davis, Matthias Zimmermann, Maxim A. Efremov, Ernst Maria Rasel, Wolfgang P. Schleich, George R. Welch, Jihane Mimih, Frank A. Narducci
Ellipse fitting is widely used in the extraction of the differential phase between atom interferometers amid substantial common phase noise. This study meticulously examines the dependency of extraction noise on the differential phase between atom interferometers during ellipse fitting. It reveals that the minimum extraction noise can manifest at distinct differential phases, contingent upon the dominance of different noise types. Moreover, the outcomes are influenced by whether the interferometers undergo simultaneous detection or not. Our theoretical simulations find empirical validation in a compact horizontal atom gravity gradiometer. The adjustment of the differential phase significantly enhances measurement sensitivity, culminating in a differential gravity resolution of 1.6 × 10−10 g @ 4800 s.
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/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.
The utility of inertial sensors depends on resilience against real-world dynamics and noise. Atom interferometry offers a sensing technology with the advantage of good long-term stability, high sensitivity, and accuracy. High measurement bandwidth improves an atom interferometer's ability to reject errors due to dynamics and noise. Here we demonstrate resilience against time-varying environmental noise by rapidly switching the direction of inertial sensitivity in the atom interferometer through a common technique known as k-reversal. We demonstrate sub-interrogation-time k-reversal at 592 Hz in a cold-beam atomic interferometer with an inverse interrogation time of 148 Hz. The interferometer fringe output is read out continuously and post-processed using nonlinear Kalman filters to determine both the inertial and error contributions to the output phase. The resulting power spectral densities show a significant reduction of phase error due to a noisy magnetic field as the k-reversal frequency increases.