Enhanced heralded single-photon source with a photon-number-resolving parallel superconducting nanowire single-photon detector

TL;DR

This paper demonstrates that high-efficiency photon-number-resolving superconducting nanowire detectors can improve heralded single-photon sources by reducing multiphoton emissions and increasing heralding rates, while also enabling precise photon-number measurements.

Contribution

The study introduces the use of a high-efficiency PNR SNSPD as a heralding detector, enhancing HSPS performance and simplifying photon-number distribution measurements.

Findings

Reduced $g^{(2)}(0)$ by 26.6% using PNR filtering

Increased heralding rate by 36.3% at fixed $g^{(2)}(0)$

Accurate photon-number distribution measurement with a single PNR detector

Abstract

Heralded single-photon sources (HSPS) intrinsically suffer from multiphoton emission, leading to a trade-off between the source's quality and the heralding rate. A solution to this problem is to use photon-number-resolving (PNR) detectors to filter out the heralding events where more than one photon pair is created. Here, we demonstrate the use of a high-efficiency PNR superconducting nanowire single-photon detector (SNSPD) as a heralding detector for a HSPS. By filtering out higher-order heralding detections, we can reduce the $g^{(2)}(0)$ of the heralded single photon by $(26.6 \pm 0.2)\,\%$, or alternatively, for a fixed pump power, increasing the heralding rate by a factor of $1.363 \pm 0.004$ for a fixed $g^{(2)}(0)$. Additionally, we use the detector to directly measure the photon-number distribution of a thermal mode and calculate the unheralded $g^{(2)}(0)$. We show the possibility to perform $g^{(2)}(0)$ measurements with only one PNR detector, with the results in agreement with those obtained by more common-place techniques which use multiple threshold detectors. Our work shows that efficient PNR SNSPDs can significantly improve the performance of HSPSs and can precisely characterize them, making these detectors a useful tool for a wide range of optical quantum information protocols.