Abstract
AbstractSingle‐photon sources (SPSs) based on quantum emitters hold promise in quantum radiometry as metrology standard for photon fluxes at the low light level. Ideally this requires control over the photon flux in a wide dynamic range, sub‐Poissonian photon statistics, and narrow‐band emission spectrum. In this work, a monochromatic SPS based on an organic dye molecule is presented, whose photon flux is traceably measured to be adjustable between 144 000 and 1320 000 photons per second at a wavelength of (785.6 ± 0.1) nm, corresponding to an optical radiant flux between 36.5 and 334 fW. The high purity of the single‐photon stream is verified, with a second‐order autocorrelation function at zero time delay below 0.1 throughout the whole range. Such molecule‐based SPS is hence used for the calibration of a single‐photon avalanche detector against a low‐noise analog photodiode traceable to the primary standard for optical radiant flux (i.e., the cryogenic radiometer). Due to the narrow bandwidth of the source, corrections to the detector efficiency arising from the spectral power distribution are negligible. With this major advantage, the developed device may finally realize a low‐photon‐flux standard source for quantum radiometry.
Highlights
Sources of single photons are required for level
We report on the optimized and metrologically characterized photon flux from a SPS based on a dibenzoterrylene (DBT) molecule in an anthracene (Ac) nanocrystal, exhibiting strong anti-bunching in the photon statistics, as well as narrow-band, bright, and photostable emission
In this paper we demonstrate the realization of an absolute SPS based on the emission of an organic dye molecule operated at cryogenic temperature
Summary
The ments.[5] Notably, they turn out to be ideal high purity of the single-photon stream is verified, with a second-order autocorrelation function at zero time delay below 0.1 throughout the whole range Such molecule-based SPS is used for the calibration of a single-photon avalanche detector against a low-noise analog photodiode sources for radiometry, especially in quantum radiometry, where low photon fluxes (in the fW range) have to be measured with low uncertainty. A direct calibration could not be carried out because of the low photon rate (60 kphoton/s), associated to an overall efficiency of η ≈ 0.1% In this respect, sources based on semiconductor quantum dots[14] or molecules[15] in cryogenic environment look currently more suitable for applications. (count/s) we refer to the count rate of a SPADs, while “photons per second” (photon/s) refers to the photon flux, evaluated as the count rate read by the detector divided by its quantum efficiency
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