US 7,492,904 B2
QKD system detector autocalibration based on bit-error rate
Jonathan Young, Newburyport, Mass. (US)
Assigned to MagiQ Technologies, Inc., New York, N.Y. (US)
Filed on Apr. 20, 2005, as Appl. No. 11/110,227.
Prior Publication US 2006/0239460 A1, Oct. 26, 2006
Int. Cl. H04L 9/00 (2006.01); H04K 1/00 (2006.01)
U.S. Cl. 380—278  [380/277; 380/255] 20 Claims
OG exemplary drawing
 
1. A method of autocalibrating a quantum key distribution (QKD) system having operably coupled encoding stations and a single-photon detector (SPD) unit in one of the stations, the method comprising:
a) performing a detector gate signal timing scan by sending a detector gate signal to the SPD unit and varying an arrival time T of the detector gate signal over a first range R1 to determine an optimum arrival time TMIN that corresponds to an optimum bit-error rate (BER) of BERMIN for photon signals exchanged between the two encoding stations; and
b) performing detector gate signal timing dithering by varying the arrival time T over a second range R2 surrounding TMIN to maintain the BER at or near BERMIN.