Toward a Laser‐Free Diamond Magnetometer for Microwave Fields

Abstract

AbstractThe nitrogen‐vacancy (NV) center in diamond is a unique magnetometer. Its atomic size enables integrations of a tremendous amount (nNV) of NV centers in a bulk diamond with a sensitivity scaling as . However, such a bulk sensor requires a high‐power laser to polarize and read out the NV centers. The increasing thermal damage and additional noises associated with high‐power lasers hinder the growth of nNV, and thus limit the sensitivity at picotesla level. Here, it shows a relaxometry‐based microwave magnetometer that the power density is determined by the relaxation time T1. By cooling the diamond sensor to prolong the T1 (≈s), the required power density further reduces to , of the saturation value. This work paves the way for the utilization of large‐size diamond to promote the sensitivity of diamond magnetometer to femtotesla level and beyond.