Modulation of the Differential Phase in Atom Gravity Gradiometer via a Bias Magnetic Field

The gravity gradient field serves as a pivotal geophysical indicator, with its high-precision signals holding profound implications for endeavors such as resource detection, subterranean exploration, and autonomous navigation. The atom gravity gradiometer (AGG), a cutting-edge instrument leveraging atom interferometry (AI), has been designed to surpass traditional atom gravimeters in terms of resolution and noise mitigation capabilities. The AGG’s signal extraction process predominantly hinges on elliptical fitting techniques to ascertain the differential phase. Despite its commendable efficiency, this approach encounters limitations, particularly when the differential phase equals an integer multiple of $\pi $ , necessitating phase modulation. Enhancing the differential phase of the AGG through modulation can significantly elevate the measurement accuracy and expand the operational envelope of gravity gradiometers. We introduce an innovative modulation technique that capitalizes on the quadratic Zeeman effect induced by magnetic fields to create phase variances, ensuring that modulation precision remains impervious to fluctuations in current sources. The experimental results underscore a notable differential phase alteration, which aligns precisely with the theoretical models we have adeptly integrated into our approach.