Nonclassical 2-photon interference with separate intrinsically narrowband fibre sources

TL;DR

This paper presents a novel narrowband fibre-based photon pair source enabling high-efficiency, unfiltered two-photon interference, advancing quantum photonics by producing pure heralded photons from separate sources.

Contribution

It demonstrates the first Hong-Ou-Mandel interference with unfiltered photons from separate fibre sources, using engineered phase matching for intrinsically factorable photon pairs.

Findings

Achieved up to 21% detection efficiency per photon.

Produced photon pairs at 597 nm and 860 nm with no spectral correlations.

First demonstration of unfiltered two-photon interference from separate fibre sources.

Abstract

In this paper, we demonstrate a source of photon pairs based on four-wave-mixing in photonic crystal fibres. Careful engineering of the phase matching conditions in the fibres enables us to create photon pairs at 597 nm and 860 nm in an intrinsically factorable state showing no spectral correlations. This allows for heralding one photon in a pure state and hence renders narrow band filtering obsolete. The source is narrow band, bright and achieves an overall detection efficiency of up to 21% per photon. For the first time, a Hong-Ou-Mandel interference with unfiltered photons from separate fibre sources is presented.