Optical addressing of individual targets in solids

This disclosure concerns photonics and in particular the addressing of individual targets in solids. In aspect one there is provided a device comprising a solid substrate with one or more atomic scale targets in the substrate. A laser light is focused on a region of the substrate that contains a single target to selectively cause photoionization of the target. A charge sensor with sub-electron charge sensitivity is focussed on measuring the charge in the region of the substrate that contains a single target. In use, the device operates such that the laser is turned on to cause photoionization of the target, and the charge sensor detects the change in charge in the region of the substrate that contains the single target. In another aspect is the method for optically investigating individual nuclear spin states of single atoms by investigating both the Zeeman effect and the hyperfine interaction of the single atoms.