High-sensitivity wide-field magnetic field imaging using NV-diamond

We present the first implementation of wide-field magnetic imaging based on the Ramsey protocol and a high density layer of nitrogen-vacancy (NV) color centers at the surface of a diamond chip. Compared to standard CW techniques for optically detected magnetic resonance (ODMR), our pulsed implementation provides enhanced sensitivity, a higher sensing bandwidth (up to \textasciitilde 100 kHz), and better noise rejection. By extending the standard Ramsey sensing scheme with advanced quantum control methods, including sensing in the NV center's double-quantum basis \textbraceleft -1,$+$1\textbraceright and spin bath control, we significantly reduce the imager's susceptibility to inhomogeneities such as crystal-lattice strain fields and microwave gradients over of the field-of-view.