| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a photodetecting method, a photodetector and a quantum cryptocommunication system which can improve a bit discrepancy rate caused by a spoofing eavesdropping. <P>SOLUTION: An optical branching means 31 branches an optical pulse string inputted to a receiver 30 through an optical transmission path 304, and one of branched optical pulse strings is delayed by two pulses with respect to the other of the branched optical pulse strings. An optical multiplexer 32 multiplexes the delayed optical pulse series with the other optical pulse string. Two outputs from the optical multiplexer 32 are respectively inputted to optical branching means 33 and 35 and respectively branched to two routes, and one of the branched optical pulse strings is delayed by one pulse with respect to the other optical pulse string. Optical multiplexers 36 and 38 multiplex the delayed optical pulse string delayed by one pulse with an undelayed optical pulse string, and photon detectors 37 to 40 detect the outputs of the optical multiplexers 36 and 38. <P>COPYRIGHT: (C)2006,JPO&NCIPI |
