Key distribution in a multiple access network using quantum cryptography
AssigneeBritish Telecommunications public limited company
InventorsPaul D. Townsend, David W. Smith
Life of this patent
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Abstract
In a method of quantum cryptography, a transmitter (T) communicates on a quantum channel with several receivers (R1-R3). The receivers are located on different branches of a common communications network The method establishes a different respective secret key for each receiver. A timing pulse may be transmitted from the transmitter to the receivers to synchronise the receivers prior to a transmission on a quantum channel. The quantum channel may be multiplexed and transmitted concurrently with classical multi-photon transmissions on the network.
Claims12
A method of communication using quantum cryptography, said method comprising:
- communicating from a transmitter on a quantum channel over a common communications network with a plurality of receivers located on the common communications network;
- and
- simultaneously establishing from a single series of transmitted modulated single photon signals different respective secret keys for a plurality of receivers.
A method of communication using quantum cryptography, said method comprising:
- communicating from a transmitter on a quantum channel over a common communications network with a plurality of receivers located on the common communications network;
- and establishing a different respective secret key for each receiver;
- the quantum channel being multiplexed with at least one classical channel carried concurrently on the network.
A method of communication using quantum cryptography, said method comprising:
- communicating from a transmitter on a quantum channel over a common communications network with a plurality of receivers located on the common communications network;
- and establishing a different respective secret key for each receiver;
- every nth pulse, where n is an integer greater than 1, being transmitted on the quantum channel with a higher intensity, the higher intensity pulses being discriminated at the receivers to provide a timing reference.
A communications system comprising:
- a transmitter,
- a plurality of receivers, and
- a multiple access network linking the transmitter to the receivers,
- wherein the transmitter includes means for generating single-photon pulses encoded in different quantum states and
- means for establishing different quantum cryptographic keys over the multiple access network simultaneously for a plurality of receivers.
Dependencies are inferred from the claim text.