Coherence measures for heralded single-photon sources

TL;DR

This paper develops a theoretical framework and experimental validation for assessing the coherence of heralded single-photon sources using time-averaged measurements, enabling better standardization without high-resolution devices.

Contribution

The paper introduces new coherence measures and analysis methods for heralded SPSs based on continuous-wave parametric down-conversion, addressing limitations of traditional $g^{(2)}$ measurements.

Findings

Validated theory with experimental data

Enhanced characterization of heralded SPS coherence

Facilitated standardization of SPSs

Abstract

Single-photon sources (SPSs) are mainly characterized by the minimum value of their second-order coherence function, viz. their $g^{(2)}$ function. A precise measurement of $g^{(2)}$ may, however, require high time-resolution devices, in whose absence, only time-averaged measurements are accessible. These time-averaged measures, standing alone, do not carry sufficient information for proper characterization of SPSs. Here, we develop a theory, corroborated by an experiment, that allows us to scrutinize the coherence properties of heralded SPSs that rely on continuous-wave parametric down-conversion. Our proposed measures and analysis enable proper standardization of such SPSs.