Department of Modern Physics and Hefei National Laboratory for Physical Sciences at the Microscale, University of Science and Technology of China, Hefei 230026, China.
Chinese Academy of Sciences (CAS) Center for Excellence and Synergetic Innovation Center in Quantum Information and Quantum Physics, University of Science and Technology of China, Shanghai 201315, China.
Science. 2017 Jun 16;356(6343):1140-1144. doi: 10.1126/science.aan3211.
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.
长距离纠缠分发对于量子物理的基础检验和可扩展量子网络都至关重要。然而，由于信道损耗，之前实现的距离被限制在~100 公里以内。在这里，我们通过两条卫星到地面的下行链路，总长度从 1600 公里到 2400 公里不等，演示了基于卫星的纠缠光子对到地球上两个相隔 1203 公里的位置的分发。在严格的爱因斯坦定域性条件下，我们观察到了双光子纠缠的存活和贝尔不等式的违反，其值为 2.37 ± 0.09。所获得的有效链路效率比通过电信光纤进行的两个光子的直接双向传输高几个数量级。
