Clock Transitions Versus Bragg Diffraction in Atom-interferometric Dark-matter Detection

TL;DR

This paper compares the sensitivity of atom interferometers using clock transitions and Bragg diffraction to detect dark matter, analyzing how dark matter interactions affect atomic internal states and motion.

Contribution

It provides a detailed analysis of how dark matter influences internal atomic transitions and external motion, highlighting differences between clock-based and diffraction-based atom interferometers.

Findings

Clock transition sensitivity depends on both mean and differential dark matter couplings.

Bragg diffraction-based sensors are mainly affected by dark matter coupling to atomic motion.

Terrestrial detectors show distinct responses based on the type of atom interferometry used.

Abstract

Atom interferometers with long baselines are envisioned to complement the ongoing search for dark matter. They rely on atomic manipulation based on internal (clock) transitions or state-preserving atomic diffraction. Principally, dark matter can act on the internal as well as the external degrees of freedom to both of which atom interferometers are susceptible. We therefore study in this contribution the effects of dark matter on the internal atomic structure and the atoms' motion. In particular, we show that the atomic transition frequency depends on the mean coupling and the differential coupling of the involved states to dark matter, scaling with the unperturbed atomic transition frequency and the Compton frequency, respectively. The differential coupling is only of relevance when internal states change, which makes detectors, e.g., based on single-photon transitions sensitive to both coupling parameters. For sensors generated by state-preserving diffraction mechanisms like Bragg diffraction, the mean coupling modifies only the motion of the atom as the dominant contribution. Finally, we compare both effects observed in terrestrial dark-matter detectors.