Entanglement swapping with independent sources over an optical-fiber network

Date: 2017-03-06
Authors Qi-Chao Sun, Ya-Li Mao, Yang-Fan Jiang, Qi Zhao, Si-Jing Chen, Wei Zhang, Wei-Jun Zhang, Xiao Jiang, Teng-Yun Chen, Li-Xing You, Li Li, Yi-Dong Huang, Xian-Feng Chen, Zhen Wang, Xiongfeng Ma, Qiang Zhang, and Jian-Wei Pan
Journal No. Phys. Rev. A 95, 032306
Abstract 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 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±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.