Quantum opto-mechanics and dark matter across disparate scales

The only things we know definitively about dark matter are roughly how much there is and that it gravitates. In particular, dark matter could have a wide range of possible masses and couplings. Quantum-limited mechanical sensors provide a robust platform to look for dark matter in many different regimes, and I will review the program of experiments emerging around this idea. After reviewing some current searches for certain light and medium-mass dark matter candidates, I will focus on the efforts of the Windchime collaboration, which aims to build an array of millions of optomechanical devices sensitive enough to search for heavy dark matter purely through its gravitational coupling.