Counterfactual Quantum Key Distribution
The task of distributing a secret key could be achieved even when the particle (on which the secret information, e.g. polarization, has been encoded) does not traverse through the quantum channel. A protocol developed by Tae-Gon Noh. Here Alice generates a photon which randomly takes either path (a) or path (b). Path (a) stays inside Alice's secure device and path (b) goes to Bob. By rejecting the photons that Bob receives and only accepting the ones he doesn't receive, Bob & Alice can set up a secure channel, i.e. Eve's attempts to read the counterfactual photons would still be detected. This protocol uses the quantum phenomenon whereby the possibility that a photon can be sent has an effect even when it isn't sent. So-called Interaction-free measurement also uses this quantum effect, as for example in the bomb testing problem, whereby you can determine which bombs are not duds without setting them off, except in a counterfactual sense.
Read more about this topic: Quantum Key Distribution Network
Famous quotes containing the words quantum, key and/or distribution:
“A personality is an indefinite quantum of traits which is subject to constant flux, change, and growth from the birth of the individual in the world to his death. A character, on the other hand, is a fixed and definite quantum of traits which, though it may be interpreted with slight differences from age to age and actor to actor, is nevertheless in its essentials forever fixed.”
—Hubert C. Heffner (19011985)
“This is not a book. This is libel, slander, defamation of character. This is not a book, in the ordinary sense of the word. No, this is a prolonged insult, a gob of spit in the face of Art, a kick in the pants to God, Man, Destiny, Time, Love, Beauty ... what you will. I am going to sing for you, a little off key perhaps, but I will sing.”
—Henry Miller (18911980)
“My topic for Army reunions ... this summer: How to prepare for war in time of peace. Not by fortifications, by navies, or by standing armies. But by policies which will add to the happiness and the comfort of all our people and which will tend to the distribution of intelligence [and] wealth equally among all. Our strength is a contented and intelligent community.”
—Rutherford Birchard Hayes (18221893)