Four pilot studies will be carried out within this project, addressing the following properties:

A. The detection efficiency of a single-photon detector:

(i) At 850 nm, on a free-space (i.e. not fibre-coupled) detector (Excelitas SPCH-AQRH);

(ii) At 1550 nm, on a fibre-coupled free-running single-photon avalanche detector (idQuantique ID220).

B. The Glauber second-order auto-correlation function of a  single-photon source:

(i) At 710 nm: emission from a nitrogen vacancy centre in diamond;

(ii) At 1550 nm: emission of a heralded single-photon source.

These pilot studies are preparation for formal comparisons which will demonstrate the degree of equivalence between measurements perfomed at different National Metrology Institutes.


Comparison A.(i) is being executed under the auspices of Taskgroup11 ‘Single-Photon Radiometry’ of the CCPR (Consultative Committee on Photometry and Radiometry) Working Group on Strategic Planning.

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The remaining comparisons were performed at INRIM, with the participation of CMI, NPL and PTB during the period 16-27 Oct 2017

Preliminary results from B(i) can be found at:

Preliminary results from B(ii) can be found at:

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