Ultralight dark matter searches at the sub-Hz frontier with atom multigradiometry

TL;DR

This paper models gravity gradient noise in atom gradiometry experiments to improve ultralight dark matter searches in the sub-Hz frequency range, proposing multigradiometer setups to enhance sensitivity.

Contribution

It introduces a likelihood-based method to incorporate gravity gradient noise into sensitivity estimates and demonstrates the potential of multigradiometers to probe new ULDM parameter space.

Findings

Gravity gradient noise can be mitigated with multigradiometer configurations.

Multigradiometers can extend the search for ultralight scalar dark matter.

The analysis applies to future experiments like AION and MAGIS-100.

Abstract

Single-photon atom gradiometry is a powerful experimental technique that can be employed to search for the oscillation of atomic transition energies induced by ultralight scalar dark matter (ULDM). In the sub-Hz regime the background is expected to be dominated by gravity gradient noise (GGN), which arises as a result of mass fluctuations around the experiment. In this work we model the GGN as surface Rayleigh waves, and we construct a likelihood-based analysis that consistently folds GGN into the sensitivity estimates of vertical atom gradiometers in the frequency window between 1 mHz and 1 Hz. We show that in certain geological settings GGN can be significantly mitigated when operating a multigradiometer configuration, which consists of three or more atom interferometers in the same baseline. Multigradiometer experiments, such as future versions of AION and MAGIS-100, have the potential to probe regions of scalar ULDM parameter space in the sub-Hz regime that have not been excluded by existing experiments.