A single-crystal source of path-polarization entangled photons at non-degenerate wavelengths

TL;DR

This paper presents a compact, high-brightness single-crystal source that generates path-polarization-entangled photon pairs at non-degenerate wavelengths with high interference visibility, suitable for quantum communication and entanglement transfer.

Contribution

The work introduces a novel, efficient single-crystal source producing entangled photons at 810 nm and 1550 nm with high rate and visibility, advancing quantum communication technologies.

Findings

Maximum rate of 3 million counts per second per THz per mW

Two-photon interference visibility above 90%

Suitable for quantum key distribution and entanglement transfer

Abstract

We demonstrate a bright, narrowband, compact, quasi-phase-matched single-crystal source generating path-polarization-entangled photon pairs at 810 nm and 1550 nm at a maximum rate of 3 Mcounts/(s THz mW) after coupling to single-mode fiber, and with two-photon interference visibility above 90%. While the source can already be used to implement quantum communication protocols such as quantum key distribution, this work is also instrumental for narrowband applications such as entanglement transfer from photonic to atomic qubits, or entanglement of photons from independent sources.