Satellite-based entanglement distribution over 1200 kilometers
Juan Yin, Yuan Wen Cao, Yu-Huai Li, Sheng‐Kai Liao, Liang Zhang, Ji-Gang Ren, Wenqi Cai, Wei-Yue Liu, Bo Li, Hui Dai, Guang-Bing Li, Qiming Lu, Yun-Hong Gong, Yu Xu, Shuang-Lin Li, Fengzhi Li, Ya-Yun Yin, Zi-Qing Jiang, Ming Li, Jianjun Jia · Science · 2017
Long-distance entanglement distribution is essential for both foundational tests of quantum physics and scalable quantum networks. Owing to channel loss, however, the previously achieved distance was limited to ~100 kilometers. Here we demonstrate satellite-based distribution of entangled photon pairs to two locations separated by 1203 kilometers on Earth, through two satellite-to-ground downlinks with a summed length varying from 1600 to 2400 kilometers. We observed a survival of two-photon entanglement and a violation of Bell inequality by 2.37 ± 0.09 under strict Einstein locality conditions. The obtained effective link efficiency is orders of magnitude higher than that of the direct bidirectional transmission of the two photons through telecommunication fibers.