Generating polarization-entangled photon pairs using cross-spliced birefringent fibers

TL;DR

This paper presents a fiber-based source of polarization-entangled photon pairs using cross-spliced birefringent fibers, achieving high fidelity and potential for fully fiber-integrated quantum communication systems.

Contribution

The work introduces a novel in-fiber polarization-entangled photon source with high fidelity, utilizing a simple splicing technique and temporal walk-off compensation.

Findings

Achieved 92.2% fidelity with Bell state

Demonstrated a fully fiber-based entangled photon source

Potential for integration into fiber-optic quantum networks

Abstract

We demonstrate a novel polarization-entangled photon-pair source based on standard birefringent polarization-maintaining optical fiber. The source consists of two stretches of fiber spliced together with perpendicular polarization axes, and has the potential to be fully fiber-based, with all bulk optics replaced with in-fiber equivalents. By modelling the temporal walk-off in the fibers, we implement compensation necessary for the photon creation processes in the two stretches of fiber to be indistinguishable. Our source subsequently produces a high quality entangled state having (92.2 \pm 0.2) % fidelity with a maximally entangled Bell state.