Imaging colour centres on the nanoscale

Scientists have imaged individual fluorescent colour centres inside a diamond lattice with an unprecedented resolution of 5.8 nanometres. The study, published online in Nature Photonics, looks set to aid the development of solid-state single-photon sources and quantum information processing.

In the past, because of the so-called diffraction-limit for imaging systems, it has been difficult to image these colour centres ? light-emitting defects that result from a nitrogen atom replacing two carbon atoms in the diamond lattice ? because they are separated by less than half the wavelength of the illumination light. Stefan Hell and co-workers have now imaged these centres using stimulated emission depletion microscopy ? which overcomes the limitation by depleting the fluorescence of the objects around a target, leaving only the target to fluoresce. They achieve a resolving power of 5.8 nanometres, which is over 100 times smaller than the wavelength of the illumination light. They were also able to determine the location of the defects with a precision of the order of tenths of nanometres.