Quantum sensing methods for directional dark matter detection

Detectors searching for weakly interacting massive particle (WIMP) dark matter (DM), which have traditionally grown more sensitive with increasing mass and better background reduction, will soon face an irreducible background: detection of solar neutrinos, or the "neutrino floor". Directional detectors would surpass this "floor" by differentiating particles originating from the sun or the galactic halo. We are developing methods for directional detection in diamond, an attractive detector material because of its favorable sensitivity profile and good semiconductor properties. Nuclear recoils in such a detector would leave "tracks" of crystal damage and lattice strain, serving as a durable record of the initiating particle's direction; detecting and mapping these sub-micron tracks is one of the central challenges of such a detector. Over the past two years, we have demonstrated quantum sensing protocols using nitrogen-vacancy centers to measure diamond crystal strain with the sensitivity required to identify such tracks, as well as x-ray microscopy methods with the resolution required to extract their direction once identified. In this talk, we will present these recently published results, as well as prospects for a next-generation three-dimensional strain microscope.