Nuclear Magnetic Resonance Microscopy with a Wide Field of View*

Paramagnetic defect centers have emerged as capable quantum sensors due to advances in control and sensing protocols, as well as in material science. Especially nitrogen-vacancy (NV) centers in diamond have proven to be sensitive probes of magnetic fields and other physical quantities, enabling their use in electron and nuclear paramagnetic resonance of other spin species within volumes of a few cubic nanometers. Mostly single NV centers are used in scanning microscopy but the detection can be multiplexed by interrogating thin layers of implanted NV center ensembles with a scientific camera. We use such a wide field imaging mode to detect the nuclear magnetic signal from solid state thin films deposited on the diamond surface. We demonstrate how parallel orchestration of the ensemble can be regained even within strong gradients of the microwave control field, which are inherent to tightly integrated ensemble implementations. We mitigate differences in Rabi frequency up to a factor of three by using optimal control microwave pulses. Conversely, inhomogeneities of the control field can be exploited to obtain sub-diffraction limited spatial resolution.