Patent ID: 8059964

Claim:
A method of operating a quantum key distribution (QKD) system that includes first and second QKD stations (Alice and Bob) optically coupled to one another, with Bob comprising a controller, a detector unit and a phase modulator MB, the method comprising: setting a timing T SS of synchronization (sync) signals SS that travel between Alice and Bob; sending optical signals from Alice to Bob to establish a timing T SB of a phase modulator activation signal SB for the phase modulator MB and a timing T S40 of a detector gating signal S 42 for the detector unit based on said sync signals SS, wherein established timings T SB and T S40 correspond to maximum number of optical signal detector counts N MAX of the optical signals; fixing a relative timing Î”T F1 between the signals SB and S 42 so that a change in sync signal timing T SS does not change Î”T F1 ; and after fixing the relative timing Î”T F1 , operating the QKD system using quantum signals, and dithering the timing T SS of the synchronization signals SS to maintain an optimum sync signal timing T SS without changing the relative timing Î”T F1 between signals SB and S 42 .