Figure 3: Deterministic assembly and characterization of a single NV centre inside a VG channel.

(a) AFM image of NDs positioned in the vicinity of a VG. The solid and dashed circles indicate, respectively, the position of one ND with a single NV and the position in the VG where it was positioned with an AFM tip. The scale bar is 5 μm. (b) AFM scan of the ND inside the VG channel. The scale bar is 500 nm. (c–d) Confocal fluorescence microscopy images of the VG and surrounding array of NDs before and after AFM manipulation of the ND hosting a single NV centre. The map in (d) evidences the presence of the ND inside the VG. To enhance the contrast of the NV centre fluorescence, this image was acquired when the excitation polarization was set parallel to the VG main axis as this configuration reduces the Au auto-fluorescence of the VG. The scale bars are 5 μm. (e) Lifetime measurements of the selected NV centre under 532 nm green pulsed laser excitation at three different positions: initial and intermediate positions at the Au surface (blue and green) and inside the VG (orange). (f) Second order autocorrelation of the selected ND. The presence of a dip at zero time delay (t=0) shows the quantum nature of the NV. For the selected particle, g²(t=0)<0.5 unambiguously demonstrates the presence of only one single NV centre inside the ND.