The invisible drummer: a search for ultralight dark matter with a membrane

Optomechanical accelerometers have been proposed as detectors for vector ultralight dark matter. In this talk we present a cryogenic dark matter search using a resonant detector based on cm-scale nanomechanical membranes. Operating in a closed-cycle cryostat, we implement a custom vibration isolation system to suppress acoustic vibrations and enable thermalization to 4 K, and use photothermal frequency tuning to improve resonant detection bandwidth. We perform an analysis of the detector’s measured acceleration spectrum to search for dark matter signals around 40 kHz, corresponding to particle mass near 10^-10 eV/c².