All-fibre multiplexed source of high-purity heralded single photons

TL;DR

This paper presents a fibre-integrated, multiplexed heralded single photon source that combines active switching and dispersion engineering to produce high-purity, near-deterministic single photons suitable for scalable quantum photonics.

Contribution

It introduces a complete fibre-based system integrating nonlinear material, dispersion control, and fast switching for high-purity, scalable single photon generation.

Findings

Achieved high-purity single photon generation with minimal frequency correlation.

Implemented active multiplexing to enhance deterministic photon delivery.

Developed a low-loss, alignment-free fibre-integrated device.

Abstract

Single photon sources based on spontaneous photon-pair generation have enabled pioneering experiments in quantum optics. However, their non-determinism presents a bottleneck to scaling up photonic and hybrid quantum-enhanced technologies. Furthermore, photon pairs are typically emitted into many correlated frequency modes, producing an undesirable mixed state on heralding. Here we present a complete fibre-integrated heralded single photon source that addresses both these difficulties simultaneously. We use active switching to provide a path to deterministic operation by multiplexing separate spontaneous sources, and dispersion engineering to minimise frequency correlation for high-purity single photon generation. All the essential elements -- nonlinear material with dispersion control, wavelength isolation, optical delay, and fast switching -- are incorporated in a low-loss alignment-free package that heralds photons in telecoms single-mode fibre. Our results demonstrate a scalable approach to delivering pure single photons directly into guided-wave photonic devices.