[roywiggins]

Quantum entanglement can't be used to send information without also sending some photons or other signal between two locations. That's one problem Einstein had with entanglement- at the time, it looked like entanglement might let you send information "at a distance" without transmitting anything. It turns out that entanglement is real but it conspires to prevent any entangled correlations from actually conveying classical information on their own.[0]

The idea behind quantum cryptography is to send photons from A to B that are specially prepared so that any attempt to read those photons in flight would be detected. You use these photons to pick a shared key, and then communicate between A and B using that key via a classical channel. If you detect someone snooping on the initial key exchange, you can toss that key and try again.

[0] https://en.wikipedia.org/wiki/No-communication_theorem