| 摘要 |
A communication system uses single-channel quantum cryptography for the secure transmission of a key. A transmitter randomly selects one of a number of encryption alphabets corresponding to different non-commutating quantum mechanical operators. The transmitter and receiver then subsequently communicate to establish which of the transmitted signals were encoded and decoded using common operators. The signals which were transmitted and received using different operators, the discarded data, are analysed and the expected and measured statistics compared to determine whether an eavesdropper has intercepted the transmission. In a preferred example, the transmitter selects from three or more different encoding alphabets comprising at least two mutually orthogonal alphabets and one other intermediate alphabet. In this case, separate statistical tests may be applied to the discarded data encoded with the orthogonal alphabets and to the discarded data encoded with the intermediate alphabet. |
