Efficient quantum cryptography network without entanglement and quantum memory

摘要

An efficient quantum cryptography network protocol is proposed withd-dimension polarized photons, without resorting to entanglement and quantummemory. A server on the network, say Alice, provides the service for preparingand measuring single photons whose initial state are |0>. The users code theinformation on the single photons with some unitary operations. For preventingthe untrustworthy server Alice from eavesdropping the quantum lines, anonorthogonal-coding technique (decoy-photon technique) is used in the processthat the quantum signal is transmitted between the users. This protocol doesnot require the servers and the users to store the quantum state and almost allof the single photons can be used for carrying the information, which makes itmore convenient for application than others with present technology. We alsodiscuss the case with a faint laser pulse.