Nitrogen-vacancy color centers in nanodiamonds as reference single-photon emitters

Quantitative and reproducible optical characterization of single quantum emitters is crucial for quantum photonic materials research, yet accounting for measurement conditions remains challenging due to a lack of an established reference standard. We propose nanodiamonds containing single nitrogen vacancy (NV^-) color centers as reliable, stable, and robust reference sources of single-photon emission. We select 4 potential reference emitter candidates from a study of thousands of NV^-centers. Candidates were remeasured at a second laboratory, correlating optical pump power and NV^-center emission intensity at saturation in addition to corresponding g⁽²⁾(0) values. A reference nanodiamond is demonstrated to account for experimental conditions, with reproducible and reliable single-photon emission, as a model for a new, to our knowledge, single-photon emitter reference standard.