| US 7,502,476 B1 | ||
| Systems and methods of enhancing QKD security using a heralded photon source | ||
| Alexei Trifonov, Boston, Mass. (US); and Ekaterina Rogacheva, Boston, Mass. (US) | ||
| Assigned to MagiQ Technologies, Inc., New York, N.Y. (US) | ||
| Filed on May 27, 2005, as Appl. No. 11/139,199. | ||
| Int. Cl. H04L 9/00 (2006.01) | ||
| U.S. Cl. 380—283 [380/256; 380/278; 380/44; 713/171] | 14 Claims |
| 1. A method of forming a key in a quantum key distribution (QKD) system having optically coupled first and second QKD stations
Alice and Bob, comprising:
generating at Alice, via a single light source that operates via spontaneous parametric down conversion using a non-linear
medium, correlated pairs of photon pulses, with one of the pulses in each pair serving as an outgoing pulse having either
a single-photon or multiple photons;
at Alice, identifying time slots and a number of photons in each outgoing pulse by detecting the other of the outgoing pulse
for each pulse pair using a photon-number-resolving (PNR) detector;
communicating the time slot identities from Alice to Bob;
altering the state of each outgoing pulse;
transmitting a block of altered-state outgoing pulses from Alice to Bob;
performing at Bob a second state alteration of each outgoing pulse received at Bob and then detecting each twice-altered outgoing
pulse;
determining at Bob a first number of detected single-photon pulses and a second number of detected multi-photon pulses using
said time slot identities; and
comparing the first and second numbers to respective probabilities of detecting said first and second numbers.
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