Characterisation of nitrogen-vacancy based single-photon sources

Nowadays single-photon sources play an important role in quantum metrology. For radiometric applications, e.g. the calibration of single photon detectors, a high photon rate and a low background emission as well as a low multi-photon emission is required. Nitrogen-vacancy (NV) based colour centres in nanodiamonds are one possible way to realize efficient single photon sources and they are promising candidates for standard sources in radiometry. At PTB, these sources are characterised with a confocal microscope setup in terms of photon rate, spectral distribution of the emission, photon rate stability and anti-bunching behaviour (g2(τ)), which is a measure for the purity of the single photon emission. We observed a count rate of about 420 kcounts per second at the detector with a high single photon emission purity, displayed by a g2(0)-value as low as 0.05. Details and further results will be presented at the conference.