High-concurrence time-bin entangled photon pairs from optimized Bragg-reflection waveguides

TL;DR

This paper demonstrates a highly entangled time-bin photon pair source using optimized Bragg-reflection waveguides, achieving high concurrence and fidelity at low pump powers for quantum communication applications.

Contribution

The study introduces an optimized semiconductor waveguide source for generating highly entangled time-bin photon pairs in the telecom band with high efficiency and low pump power.

Findings

Achieved a concurrence of 88.9% indicating strong entanglement.

Fidelity of 94.2% with a Bell state demonstrates high quality of entanglement.

Low pump power operation enhances photon-pair correlation.

Abstract

Semiconductor Bragg-reflection waveguides are well-established sources of correlated photon pairs as well as promising candidates for building up integrated quantum optics devices. Here, we use such a source with optimized non-linearity for preparing time-bin entangled photons in the telecommunication wavelength range. By taking advantage of pulsed state preparation and efficient free-running single-photon detection, we drive our source at low pump powers, which results in a strong photon-pair correlation. The tomographic reconstruction of the state's density matrix reveals that our source exhibits a high degree of entanglement. We extract a concurrence of $88.9\pm 1.8\%$ and a fidelity of $94.2 \pm 0.9\%$ with respect to a Bell state.