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Quantum cryptographic system with reduced data loss

United States Patent

5,732,139
March 24, 1998
View the Complete Patent at the US Patent & Trademark Office
A secure method for distributing a random cryptographic key with reduced data loss. Traditional quantum key distribution systems employ similar probabilities for the different communication modes and thus reject at least half of the transmitted data. The invention substantially reduces the amount of discarded data (those that are encoded and decoded in different communication modes e.g. using different operators) in quantum key distribution without compromising security by using significantly different probabilities for the different communication modes. Data is separated into various sets according to the actual operators used in the encoding and decoding process and the error rate for each set is determined individually. The invention increases the key distribution rate of the BB84 key distribution scheme proposed by Bennett and Brassard in 1984. Using the invention, the key distribution rate increases with the number of quantum signals transmitted and can be doubled asymptotically.
Lo; Hoi-Kwong (Hong Kong, HK), Chau; Hoi Fung (Hong Kong, HK)
08/ 701,785
August 26, 1996
STATEMENT OF GOVERNMENTAL INTEREST This invention was made with Government support under Contract No. DE-FG02-90ER40542 awarded by the Department of Energy. The government has certain rights in the invention.