Towards a standard procedure for the measurement of the multi-photon component in a CW telecom heralded single-photon source

TL;DR

This paper proposes a standardized method for measuring the multi-photon component in continuous-wave telecom heralded single-photon sources, crucial for their reliable use in quantum technologies.

Contribution

It introduces a strategy to quantitatively estimate the multi-photon component via the second order autocorrelation function, aiding standardization efforts.

Findings

Successful measurement of $g^{(2)}$ in a low-noise CW heralded source

Pilot study involving multiple institutions demonstrates procedure feasibility

Results support development of a robust characterization protocol

Abstract

Single-photon sources are set to be a fundamental tool for metrological applications as well as for quantum information related technologies. Because of their upcoming widespread dissemination, the need for their characterization and standardization is becoming of the utmost relevance. Here, we illustrate a strategy to provide a quantitative estimate of the multi-photon component of a single-photon source, showing the results achieved in a pilot study for the measurement of the second order autocorrelation function $g^{(2)}$ of a low-noise CW heralded single-photon source prototype (operating at telecom wavelength $\lambda=1550$ nm) realized in INRiM. The results of this pilot study, involving PTB, NPL and INRiM, will help to build up a robust and unambiguous procedure for the characterization of the emission of a single-photon source.