A few months ago, I wrote about Quantum Cryptography and Quantum Key Distribution using the ‘Observer Effect’:
http://www.managedmayhem.com/2009/05/20/quantum-cryptography-quantum-key-distribution-qkd/
I got to thinking today about how possible it would be to use this same concept of quantum state entanglement in order to communicate across long distances. My thought was, if QKD exists, why not use the entangled photons… one in a transmitter, the other in a reciever… and change the state rapidly in an ‘on / off’ pattern similar to binary? This would effectively change the state of the receiver photon, which could be observed (syn / ack) and then translated into a more classical form.
As it turns out, they are already working on it:
http://www.universetoday.com/2008/03/17/a-step-toward-quantum-communications-with-space/
http://arxiv.org/abs/0803.1871
http://www.niac.usra.edu/studies/974Morgan.html
http://arxiv.org/abs/quant-ph/0305105v1
I’d love to see this stuff in operation 20-30 years from now. 