摘要
Quantum secure direct communication(QSDC)based on entanglement can directly transmit confidential information.However,the inability to simultaneously distinguish the four sets of encoded entangled states limits its practical application.Here,we explore a QSDC network based on time–energy entanglement and sum-frequency generation.In total,15 users are in a fully connected QSDC network,and the fidelity of the entangled state shared by any two users is>97%.The results show that when any two users are performing QSDC over 40 km of optical fiber,the fidelity of the entangled state shared by them is still>95%,and the rate of information transmission can be maintained above 1 Kbp/s.Our result demonstrates the feasibility of a proposed QSDC network and hence lays the foundation for the realization of satellite-based long-distance and global QSDC in the future.
基金
This work is supported in part by the National Key Research and Development Program of China(Grant No.2017YFA0303700)
National Natural Science Foundation of China(Grant Nos.11734011,11804135,and 12074155)
The Foundation for Shanghai Municipal Science and Technology Major Project(Grant No.2019SHZDZX01-ZX06)
Project funded by China Postdoctoral Science Foundation(Grant No.2019M661476).
