Reducing $g^{(2)}(0)$ of a parametric down-conversion source via photon-number resolution with superconducting nanowire detectors

TL;DR

This paper demonstrates that using superconducting nanowire detectors with photon-number resolution significantly reduces multiphoton contributions in heralded single-photon sources, improving their quality with commercially available technology.

Contribution

It is the first to apply photon-number resolving capabilities of SNSPDs to enhance heralded single-photon sources, achieving a measurable reduction in $g^{(2)}(0)$.

Findings

13% reduction in $g^{(2)}(0)$ with SNSPDs

Improved single-photon source quality using PNR detection

Achieved with only 29.6% collection efficiency

Abstract

Multiphoton contributions pose a significant challenge for the realisation of heralded single-photon sources (HSPS) based on nonlinear processes. In this work, we improve the quality of single photons generated in this way by harnessing the photon-number resolving (PNR) capabilities of commercial superconducting nanowire single-photon detectors (SNSPDs). We report a $13 \pm 0.4 \%$ reduction in the intensity correlation function $g^{(2)}(0)$ even with a collection efficiency in the photon source of only $29.6\%$. Our work demonstrates the first application of the PNR capabilities of SNSPDs and shows improvement in the quality of an HSPS with widely available technology.