Differential phase extraction in an atom gradiometer

TL;DR

This paper introduces a method to accurately extract the differential phase in atom gradiometers using auxiliary classical sensors, achieving near-quantum-limited sensitivity even with large vibration-induced phase fluctuations.

Contribution

The proposed technique allows precise differential phase extraction without requiring perfect correlation between atomic and classical signals, applicable to various interferometer configurations.

Findings

Sensitivity close to quantum projection noise limit.

Effective phase extraction despite large vibration noise.

Applicable to diverse differential interferometer setups.

Abstract

We present here a method for the extraction of the differential phase of an atom gradiometer that exploits the correlation of the vibration signal measured by an auxiliary classical sensor, such as a seismometer or an accelerometer. We show that sensitivities close to the quantum projection noise limit can be reached, even when the vibration noise induces phase fluctuations larger than 2$\pi$. This method doesn't require the correlation between the atomic and classical signals to be perfect and allows for an exact determination of the differential phase, with no bias. It can also be applied to other configurations of differential interferometers, such as for instance gyrometers, conjugate interferometers for the measurement of the fine structure constant, or differential accelerometers for tests of the equivalence principle or detection of gravitational waves.