Proc. Natl Acad. Sci. USA 111, 14669–14674 (2014)

The scaling of spin-based quantum information devices to a large number of closely spaced units is an important requirement if such devices are to be used for control and readout of nanoscale qubits. However, traditional data acquisition and interrogation methods for determining the electron spin of these devices, such as the scanning probe method, are limited in terms of their spatial resolution and field of view. Now, Matthias Pfender and colleagues at the University of Stuttgart in Germany have demonstrated an optical super-resolution technique with wide-field parallel image acquisition for use with the nitrogen–vacancy (NV) centre in bulk diamond — an important quantum system. The researchers combined the stochastic reconstruction microscopy (STORM) technique with optically detected magnetic resonance (ODMR). The NV colour centres were exposed using microwaves and lasers with wavelengths of 532 nm and 594 nm. The frequency of the microwaves was repeatedly switched from the centre of one of the NV spectral lines to the other in synchronization with the CCD frames. To take advantage of the high spectral resolution of ODMR, the microwave power was reduced. With conventional ODMR, spatial information is not accessible using NV spin resonance spectra. However, STORM combined with ODMR allows spin resonance spectra to be assigned to individual NV centres, tagging their locations. Consequently, two NV centres with different crystallographic orientations confined within tens of nanometres were individually resolved.