Direct limits for scalar field dark matter from a gravitational-wave detector

TL;DR

This paper reports the first direct search for scalar field dark matter using a gravitational-wave detector, setting new upper limits on its coupling constants and demonstrating the potential of quantum-enhanced interferometry for dark matter detection.

Contribution

It introduces a novel method of using gravitational-wave detectors beyond quantum shot-noise limits to directly search for scalar field dark matter, significantly improving existing bounds.

Findings

Set new upper limits on scalar field dark matter coupling constants.

Improved constraints by over six orders of magnitude compared to previous direct searches.

Demonstrated the potential of quantum-enhanced interferometry for dark matter detection.

Abstract

The nature of dark matter remains unknown to date; several candidate particles are being considered in a dynamically changing research landscape. Scalar field dark matter is a prominent option that is being explored with precision instruments, such as atomic clocks and optical cavities. Here we report on the first direct search for scalar field dark matter utilising a gravitational-wave detector, which operates beyond the quantum shot-noise limit. We set new upper limits for the coupling constants of scalar field dark matter as a function of its mass, by excluding the presence of signals that would be produced through the direct coupling of this dark matter to the beamsplitter of the GEO$\,$600 interferometer. The new constraints improve upon bounds from previous direct searches by more than six orders of magnitude, and are in some cases more stringent than limits obtained in tests of the equivalence principle by up to four orders of magnitude. Our work demonstrates that scalar field dark matter can be probed or constrained with direct searches using gravitational-wave detectors, and highlights the potential of quantum-enhanced interferometry for dark matter detection.