Searching for Vector Dark Matter with an Optomechanical Accelerometer.

We consider using optomechanical accelerometers as resonant detectors for ultralight dark matter. As a concrete example, we describe a detector based on a silicon nitride membrane fixed to a beryllium mirror, forming an optical cavity. The use of different materials gives access to forces proportional to baryon (B) and lepton (L) charge, which are believed to be coupling channels for vector dark matter particles ("dark photons"). The cavity meanwhile provides access to quantum-limited displacement measurements. For a centimeter-scale membrane precooled to 10 mK, we argue that sensitivity to vector B-L dark matter can exceed that of the Eöt-Wash experiment in integration times of minutes, over a fractional bandwidth of ∼0.1% near 10 kHz (corresponding to a particle mass of 10^{-10} eV/c^{2}). Our analysis can be translated to alternative systems, such as levitated particles, and suggests the possibility of a new generation of tabletop experiments.

Searching for Scalar Dark Matter with Compact Mechanical Resonators.

Ultralight scalars are an interesting dark matter candidate that may produce a mechanical signal by modulating the Bohr radius. Recently it has been proposed to search for this signal using resonant-mass antennas. Here, we extend that approach to a new class of existing and near term compact (gram to kilogram mass) acoustic resonators composed of superfluid helium or single crystal materials, producing displacements that are accessible with opto- or electromechanical readout techniques. We find that a large unprobed parameter space can be accessed using ultrahigh-Q, cryogenically cooled centimeter-scale mechanical resonators operating at 100 Hz-100 MHz frequencies, corresponding to 10^{-12}-10^{-6} eV scalar mass range.