Proposal for the search for new spin interactions at the micrometer scale using diamond quantum sensors

Abstract

For decades, searches for exotic spin interactions have used increasingly precise laboratory measurements to test various theoretical models of particle physics. However, most searches have focused on interaction length scales of 1mm, corresponding to hypothetical boson masses of 0.2meV. Recently, quantum sensors based on nitrogen-vacancy (NV) centers in diamond have emerged as a promising platform to probe spin interactions at the micrometer scale, opening the door to explore new physics at this length scale. Here, we propose experiments to search for several hypothetical interactions between NV electron spins and moving masses. We focus on potential interactions involving the coupling of NV spin ensembles to both spin-polarized and unpolarized masses attached to vibrating mechanical oscillators. For each interaction, we estimate the sensitivity, identify optimal experimental conditions, and analyze potential systematic errors. Using multipulse quantum sensing protocols with NV spin ensembles to improve sensitivity, we project constraints that are a 5-orders-of-magnitude improvement over previous constraints at the micrometer scale. We also identify a spin-polarized test mass, based on hyperpolarized C13 nuclear spins in a thin diamond membrane, which offers a favorable combination of high spin density and low stray magnetic fields. Our analysis is timely in light of a recent preprint by Rong et al. (arXiv:2010.15667) reporting a surprising nonzero result of micrometer-scale spin-velocity interactions.