Actively switchable non-degenerate polarization entangled photon pair distribution in a dense wave-division multiplexing

TL;DR

This paper demonstrates an actively switchable, high-quality polarization-entangled photon pair source in a dense wavelength division multiplexing system, enabling flexible quantum communication channels without crosstalk.

Contribution

It introduces a novel, actively switchable entangled photon pair distribution method using a single crystal in a DWDM system, with high entanglement quality and no crosstalk.

Findings

High raw visibility (>90%) in Bell interference measurements.

CHSH inequality S parameter of 2.63±0.08 indicating strong entanglement.

Active switching of photon pairs between channels without crosstalk.

Abstract

We have realized experimentally a non-degenerate polarization-entangled photon pair distribution in a commercial telecom dense wave-division multiplexing device (DWDM) with 8 channels. A promising point of this work is that the entangled photon pair is obtained via spontaneously parametric down conversion in a single type-II periodically poled KTiOPO4 crystal without usual post-selection. Another promising advantage is that we can actively control and switch the distribution of the photon pair between different channel pairs in DWDM at will. There is no crosstalk between the different channel pair because of a limited emission bandwidth of the source. High raw visibility of greater than 90% in Bell-type interference measurement in each channel pair and the CHSH inequality S parameter of 2.63+/-0.08 prove high entanglement of our source. Our work is helpful for building quantum communication networks.