To receive in the quantum cipher key dissemination system and the synchronous mannered

摘要

PROBLEM TO BE SOLVED: To provide a quantum encryption key distribution system in which synchronism is established between a transmitter unit and a receiver unit to make constant all the time a phase relationship between an optical pulse outputted from the receiver unit and an optical pulse returned to the receiver unit.;SOLUTION: An output clock signal 304 outputted from a frequency synchronizing section 300 is sent to Alice 100 via a classic channel 403 in an optical fiber transmission line 400, simultaneously returned from a returning section 500 and sent again to Bob 200 via the classic channel 402 in the optical fiber transmission line 400. At such a time, Bob 200 detects a phase difference between the output clock signal 304 and a returned clock signal 305 returned from Bob 200 in a phase detector 303. In the phase detector 303, a signal corresponding to the detected phase difference is outputted and a high frequency component is cut by a low-pass filter 302, thereby controlling a voltage controlled oscillator 301.;COPYRIGHT: (C)2005,JPO&NCIPI