# Fibre-integrated noise gating of high-purity heralded single photons

## TL;DR

This paper introduces an all-fibre source of high-purity heralded single photons with an integrated noise gate that significantly reduces uncorrelated noise, improving photon quality without sacrificing count rates.

## Contribution

The work demonstrates a fibre-integrated noise gating technique that effectively reduces noise in heralded single photon sources, enhancing their purity and practical utility.

## Key findings

- 7-fold reduction in uncorrelated noise with no loss in coincidence rate
- Effective noise suppression benefits sensitive applications and entangled state generation
- All-fibre implementation improves integration and stability

## Abstract

We present an all-fibre source of high-purity heralded single photons with an integrated conditional optical gate that reduces uncorrelated noise by almost an order of magnitude. Generating photon pairs by four-wave mixing in photonic crystal fibre, we observe with the noise gate active a factor of 7 reduction in the rate of single counts in the heralded channel with no measurable drop in coincidence count rate. In contrast to electronic post-selection of coincidence events, the real reduction in the flux of unwanted photons is beneficial for example to avoid bleaching light-sensitive samples or in generating entangled states.