Efficient Quantum Cryptography Network without Entanglement and Quantum Memory
LI Chun-Yan1,2, LI Xi-Han1,2, DENG Fu-Guo1,2,3, ZHOU Ping1,2, LIANG Yu-Jie1,2, ZHOU Hong-Yu1,2,3
1The Key Laboratory of Beam Technology and Material Modification of Ministry of Education, Beijing Normal University, Beijing 100875
2Institute of Low Energy Nuclear Physics, and Department of Material Science and Engineering, Beijing Normal University, Beijing 100875
3Beijing Radiation Center, Beijing 100875
Efficient Quantum Cryptography Network without Entanglement and Quantum Memory
LI Chun-Yan1,2;LI Xi-Han1,2;DENG Fu-Guo1,2,3;ZHOU Ping1,2;LIANG Yu-Jie1,2;ZHOU Hong-Yu1,2,3
1The Key Laboratory of Beam Technology and Material Modification of Ministry of Education, Beijing Normal University, Beijing 100875
2Institute of Low Energy Nuclear Physics, and Department of Material Science and Engineering, Beijing Normal University, Beijing 100875
3Beijing Radiation Center, Beijing 100875
Abstract： An efficient quantum cryptography network protocol is proposed with $d$-dimensional polarized photons, without resorting to entanglement and quantum memory. A server on the network, say Alice, provides the service for preparing and measuring single photons whose initial state are |0>. The users code the information on the single photons with some unitary operations. To prevent the untrustworthy server Alice from eavesdropping the quantum lines, a nonorthogonal-coding technique is used in the process that the quantum signal is transmitted between the users. This protocol does not require the servers and the users to store the quantum states and almost all of the single photons can be used for carrying the information, which makes it more convenient for application than others with present technology. We also discuss the case with a faint laser pulse
2006, Vol. 23 
