Experimental Constraints on Exotic Spin-Dependent Interactions by a Magnetometer with Ensembles of Nitrogen-Vacancy Centers in Diamond

Abstract

Improved constraints on exotic spin-dependent interactions are established at the micrometer scale by a magnetometer with ensembles of nitrogen-vacancy (NV) centers in diamond. A thin layer of NV electronic spin ensembles is utilized as the sensor, and a lead sphere is taken as the source of the nucleons. The exotic spin-dependent interactions are explored by detecting the possible effective magnetic fields by the sensor. Stringent bounds on an exotic parity-odd spin- and velocity-dependent interaction are set within the force range from 5 to 500 $\mu$m. The upper limit of the corresponding coupling constant, $g_A^eg_V^N$, is improved by more than three orders of magnitude at 330 $\mu$m. Improved constraints of $P, T$-violating scalar-pseudoscalar nucleon-electron interactions, are established within the force range from 6 to 45 $\mu$m. The limit of the corresponding coupling constant, $g_S^Ng_P^e$, is improved by more than one order of magnitude at 30 $\mu$m. Our result shows that a magnetometer with a NV ensemble can be a powerful platform for probing exotic spin-dependent interactions.