Photon number statistics of NV centre emission

Optical sources that deterministically produce single photons with a high suppression of multi-photon emission and a negligible background component are promising candidates for standard sources for quantum metrology, quantum communication and foundations of quantum mechanics. In this paper, the photon number distribution of non-classical light emitted by nitrogen vacancy (NV) centres in nano-diamonds is studied by three different experimental techniques. The photon number resolving transition edge sensor (TES) detector and the On/Off detection method are applied to determine the diagonal elements of the optical density matrix. From the data measured by the two methods the second order correlation function at time delay zero is calculated and compared with the g ²(0)-values obtained by Hanbury Brown-Twiss (HBT) interferometric measurements. Among the g ²(0)-values evaluated with the three techniques, we found good agreement in the results for a single photon emitter with a g ²(0)-value close to zero and a multi-photon source with a g ²(0)-value of approximately 0.5.