Fig. 5: Local charge-state control with high spatial resolution.

a Confocal image showing highly efficient charge-state control of arbitrarily selected NVs. The target NVs are denoted by the black dashed circles. Scale bar: 1 μm. b Charge state control of a NV dimer with a separation beyond the diffraction limit. The manipulated NV is denoted by 2. Scale bar: 0.6 μm. Upper panel: Line profile across the dimer and the corresponding Gaussian fit, yielding a separation distance of ~174 nm. Inset: Simulated confocal image of the NV dimer. Scale bar: 250 nm. c Schematic graph demonstrating the basic principle of charge-state transition imaging. The AFM tip with a high field gradient is able to control the charge state of NV with high spatial resolution. The green shade denotes excitation laser, while the semi-circled curves denote electrostatic potential contour from the conducting tip. The dashed lines indicate the built-in electric field. d Charge-state transition image of a single NV. Upper panel: A disk-like structure was obtained when scanning the metal tip with a high positive bias (+90 V). The edge of the disk reflects the NV⁺/NV⁰ transition. Middle panel: The zoomed-in image as denoted by the black dashed rectangle in the upper panel. Lower panel: The profile along the red dashed line depicted in the middle panel. After subtracting a linear slope, the line profile was fitted by a step function, yielding a spatial resolution of 4.6 nm for charge-state control.