Method and apparatus for polarisation-insensitive quantum cryptography
CA 2254767 C · Owner: British Telecommunications Public Limited Company · Inventors: Townsend, Paul David
Overview
Its claims, description and drawings are in the Canadian Patents Database.
Open the CIPO recordAbstract From the Canadian patent
A communication system uses quantum cryptography for the secure distribution of a key. A single-photon signal is phase-modulated and transmitted over a pair of time-multiplexed transmission paths. With each original single-photon signal in a given one of the transmission paths a duplicate signal is , transmitted. The duplicate is identically modulated and orthogonally polarised. At the receiver, the outputs of the two paths are combined interferometrically. A single polarisation-insensitive measurement is derived from the combined contributions of the orthogonally polarised signals.
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Listed from its CIPO record in Patent Yard's archive of Canadian patents past their term. Its claims, description and drawings are in the CIPO record and on Google Patents, and the Claude kit works from them.
Why it's free to use
- Filed May 19, 1997 and granted April 16, 2002. A Canadian patent filed from October 1, 1989 lasts 20 years from filing, so its term ended May 19, 2017.
- A certificate of supplementary protection adds at most two years for a drug, so even that would have ended by May 19, 2019.
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Timeline
Timeline From CIPO dates
Sources & verification
Official CIPO records
Everything on this page comes from the CIPO record linked above. Contains information licensed under the Open Government Licence – Canada.