Quantum Key Distribution - Counterfactual Quantum Key Distribution

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

Famous quotes containing the words quantum, key and/or distribution:

    But how is one to make a scientist understand that there is something unalterably deranged about differential calculus, quantum theory, or the obscene and so inanely liturgical ordeals of the precession of the equinoxes.
    Antonin Artaud (1896–1948)

    The safety of the republic being the supreme law, and Texas having offered us the key to the safety of our country from all foreign intrigues and diplomacy, I say accept the key ... and bolt the door at once.
    Andrew Jackson (1767–1845)

    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 (1822–1893)