Long-Distance Entanglement Purification for Quantum Communication

High-quality long-distance entanglement is essential for both quantum communication and scalable networks. Entanglement purification to distill high-quality from low-quality in a noisy environment it plays key role repeaters. The previous significant experiments require two pairs of entangled states were demonstrated table-top. Here we propose report high-efficiency using only one pair hyperentangled states. We also demonstrate its practical application entanglement-based distribution (QKD). One polarization spatial-mode hyperentanglement was distributed over 11 km multicore fiber (noisy channel). After purification, the fidelity arises 0.771 0.887 effective rate QKD increases 0 0.332. values Clauser-Horne-Shimony-Holt (CHSH) inequality 1.829 2.128. Moreover, by deterministic controlled-NOT gate, total efficiency can be estimated as 6.6x10^3 times than experiment with spontaneous parametric down-conversion (SPDC) sources. Our results offer potential implemented part full repeater large scale network.