Resolution of the Co-Location Problem in Satellite Quantum Tests of the Universality of Free Fall

TL;DR

This paper proposes a mitigation strategy combining compensation and signal demodulation to significantly reduce initial condition sensitivities in satellite quantum tests of the Universality of Free Fall, enabling more precise measurements.

Contribution

It introduces a novel scheme to mitigate gravity-gradient effects in atom-interferometric UFF tests, relaxing initial kinematic requirements by five orders of magnitude.

Findings

Initial kinematic requirements relaxed by five orders of magnitude.

Differential acceleration uncertainty reduced below 10^{-18}.

Feasibility demonstrated with moderate parameters.

Abstract

A major challenge common to all Galilean drop tests of the Universality of Free Fall (UFF) is the required control over the initial kinematics of the two test masses upon release due to coupling to gravity gradients and rotations. In this work, we present a two-fold mitigation strategy to significantly alleviate the source preparation requirements in space-borne quantum tests of the UFF, using a compensation mechanism together with signal demodulation. To this end, we propose a scheme to reduce the gravity-gradient-induced uncertainties in an atom-interferometric experiment in a dedicated satellite mission and assess the experimental feasibility. We find that with moderate parameters, the requirements on the initial kinematics of the two masses can be relaxed by five orders of magnitude. This does not only imply a significantly reduced mission time but also allows to reduce the differential acceleration uncertainty caused by co-location imperfections below the $10^{-18}$ level.