Entanglement swapping with independent sources over an optical-fiber network
Qi-Chao Sun, Ya-Li Mao, Yang-Fan Jiang, Qi Zhao, Sijing Chen, Wei Zhang, Weijun Zhang, Xiao Qiang Jiang, Teng‐Yun Chen, Lixing You, Li Li, Yidong Huang, Xianfeng Chen, Zhen Wang, Xiongfeng Ma, Qiang Zhang, Jian-Wei Pan · Physical Review A · 2017
Establishing entanglement between two remote systems by the method of entanglement swapping is an essential step for a long-distance quantum network. Here we report a field-test entanglement swapping experiment with two independent telecommunication band entangled photon-pair sources over an optical fiber network in Hefei. The two sources are located at two nodes that are $12.5\phantom{\rule{4pt}{0ex}}\mathrm{km}$ apart and the Bell-state measurement is performed at a third location which is connected to the two source nodes with 14.7-km and 10.6-km optical fibers, respectively. The observed average visibility is $79.9\ifmmode\pm\else\textpm\fi{}4.8%$, which is sufficient for the violation of Bell inequalities. Furthermore, with the swapped entanglement, we demonstrate a source-independent quantum key distribution, which is also immune to any detection attacks at the measurement site.