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Comment by d_theorist | Hacker News Reader

I had thought that quantum entanglement could not be used for communication because the state that is transmitted is random, and cannot be controlled at either end.

But, there are quotes in this article to the contrary. e.g.:

“Such a network will enable secure communication without having to worry about eavesdropping, and allow distant quantum computers to connect,” says Tittel.

Was my understanding mistaken?

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I took a quantum optics course once. It's true what you say that entanglement can't be used to communicate (by itself), hence no problems with relativity, speed of light etc. This is known as the No-communication theorem:

https://en.wikipedia.org/wiki/No-communication_theorem

But together with a conventional communications channel (e.g. radio signals), you can use quantum entanglement to create a secure communications channel. This combination is called quantum teleportation (as opposed to just quantum entanglement):

https://en.wikipedia.org/wiki/Quantum_teleportation

Right, "Did you get it?" doesn't need to confirm the information transferred

It isn't directly usable for communication, but you can use the shared random state as a one-time pad for provably-secure communication over nonsecure conventional channels.

Oh! Because both ends have access to the same random bits. Thanks.

Somewhat related, China has launched the first quantum communications satellite which is meant to prevent eavesdropping using Quantum Key Distribution, http://www.nytimes.com/2016/08/17/world/asia/china-quantum-s...

If all you send is more like a checksum or a quantum salt, a few bits of entirely-secure-in-transit entropy in the encryption key could be enough to guarantee secure end-to-end communications in the moment.

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