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arXiv · 2101.07441

Long-distance entanglement purification for quantum communication

Xiao-Min Hu·Cen-Xiao Huang·Yu-Bo Sheng·Lan Zhou·Bi-Heng Liu·Yu Guo·Chao Zhang·Wen-Bo Xing·Yun-Feng Huang·Chuan-Feng Li·Guang-Can Guo
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Abstract

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

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Xiao-Min Hu, Cen-Xiao Huang, Yu-Bo Sheng, Lan Zhou, Bi-Heng Liu, Yu Guo, Chao Zhang, Wen-Bo Xing, Yun-Feng Huang, Chuan-Feng Li, Guang-Can Guo. 2021-01-19. Long-distance entanglement purification for quantum communication. https://doi.org/10.1103/physrevlett.126.010503

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