Magnetic Sensing with Large Ensembles of Nitrogen-Vacancy Centers in Diamond

Nitrogen-vacancy (NV) centers are crystal defects in diamond which, even unshielded at room temperature, are highly sensitive to magnetic fields. The biocompatibility of diamond makes for promising applications in biophysics, where nerve signals can be sensed and imaged at close range.
In this work, a practical, compact magnetic sensing device is presented, which contains the key elements of an NV sensor in a box that fits in the palm of one’s hand.
Then, in exploration of the limits of its sensitivity, improvements are demonstrated with two approaches. First, optimal control methods are used to better manipulate the quantum spin state of diverse NV centers. Then laser beam shaping is used to improve the measurement of their spin states by the fluorescence they emit. These results indicate a promising approach for heightened sensitivity of future NV-based devices.