Searching for vector dark matter with an optomechanical accelerometer

Ultralight dark matter might produce a weak vector force on terrestrial bodies in proportion to their neutron mass. We consider searching for this signal with optomechanical accelerometers, a technology being pursued in a diversity of platforms ranging from levitated microspheres to whispering gallery mode resonators. As a concrete example, we envision an accelerometer based on a silicon nitride membrane fixed to a beryllium mirror, forming an optical cavity. For a centimeter-scale membrane pre-cooled to 10 mK, we argue that sensitivity to vector dark matter can exceed that of torsion balance equivalence principle tests in integration times of minutes, over a small range of frequencies near 10 kHz mechanical resonance frequency (corresponding to a dark matter particle mass of 10⁻¹⁰ eV/c²). Addressing challenges such as frequency tunability (to increase bandwidth) and array-based detection could enable these and similar optomechanical detectors to occupy a niche in the search for dark matter.

[1] Manley, J., Chowdhury, M. D. et al. "Searching for vector dark matter with an optomechanical accelerometer." arXiv preprint arXiv:2007.04899 (2020).