Polarization-entangled photon-pair source obtained via type-II non-collinear SPDC process with PPKTP crystal

TL;DR

This paper presents a stable, tunable polarization-entangled photon-pair source using type-II non-collinear SPDC in PPKTP, achieving high brightness and entanglement quality with temperature control and a stable interferometric setup.

Contribution

It introduces a novel non-collinear configuration with a PPKTP crystal for stable, tunable entangled photon-pair generation with high brightness and entanglement fidelity.

Findings

Brightness of 4.2 kHz/mW achieved

Concurrence of 0.975 measured

Wavelength tunability via temperature control

Abstract

We demonstrate a polarization-entangled photon-pair source obtained via a type-II non-collinear quasi-phase-matched spontaneous parametric down-conversion process with a 10-mm periodically poled KTiOPO$_4$ crystal, which is as stable and wavelength-tunable as the well-known Sagnac configuration scheme. A brightness of 4.2 kHz/mW is detected and a concurrence of 0.975 is estimated using quantum state tomography. Without loss of entanglement and brightness, the photon-pair wavelengths are tunable through control of the crystal temperature. This improvement is achieved using the non-collinear configuration and a stable interferometric distinguishability compensator.