Science
In reply to the discussion: Quantum Entanglement, Dark Counts, Coincidence Detection [View all]mindwalker_i
(4,407 posts)Quantum encryption is available, although quite expensive. I think banks use it between themselves, but it definitely isn't used by end users like us. And like I say, this is going to be possibly more difficult to get to end users, and it's limited in distance to about 10km since light tends to lose entanglement in fiber after that. Having said that, it would be really cool to set up <10km links between people and places. One possibility would be to take communications from many sources (non-quantum, run of the mill network), bundle them all together and send that over a quantum link, then unbundle it and send each packet on its way. That or some variation might offer at least an unbreakable link.
But even with such a link, it's still impossible to avoid making a time machine - although it can be a forward-time machine or a backwards-time machine. If the interferometer is next to the source of entangled photons and the other photons are sent through fiber to a remote location, the decision to keep or destroy the interference will be made after said interference is detected (or not). This means that if a bunch of these links were used in the Internet, latency could actually be negative. That would be really interesting.
So yeah, I understand the mind-bending aspects that this experiment could open up. That's why it's come to the point where I can't not work on it - I'll go crazy if I don't even try to make it work. I was going crazy waiting for Cramer to say something!