Nano Lett. 14, 1982–1986 (2014)

The development of diamond-based quantum optical devices has advanced significantly with the report of implanted nitrogen–vacancy centres in diamond possessing excellent optical coherence properties. Y. Chu and co-workers from the USA, Switzerland and the UK describe how, by employing a combination of ion implantation, high-temperature annealing and surface treatment, they could realize nitrogen–vacancy centres with lifetime-limited optical linewidths. The researchers comment that they managed to suppress spectral diffusion by using annealing and surface treatment to create a diamond environment that is nearly free from defects, which contribute to charge fluctuations. Linewidths as narrow as a few hundred megahertz were measured in a diamond sample with a nitrogen dose of 1011 cm−2 and an estimated doping depth of 10 nm. The ability to place nitrogen–vacancy centres with high-quality optical properties in a well-defined layer bodes well for the development of devices based on this approach.