[IgorPartola]

It’s worse than that. You have a pair of photons. You have no idea what state they are in because they aren’t. You send me one. You cannot influence if I’ll get it in the 1 or the 0 state. All you can do is later measure your photon and see what state it’s in and that will tell you what state my photon is in. It won’t let you transmit information IIUC and it won’t let you travel faster than light. It might help with time sync (when I measure my photon yours collapses instantly so we can synchronize an event), or synchronize some arbitrary key material: you send me a bunch of photons and then measure yours. I now know exactly what bits you have because they are the opposite of mine and we can use that for cryptography. I know that nobody snooped on this because any measurement would have collapsed the photons.

[jrootabega]

You actually have no idea when and if the other entangled thing was measured. I'm at my limits of understanding, but I believe it makes no difference when you collapse them. You could do it before moving them apart and the whole process is the same. In fact, process is probably an inadequate word. The particles always shared a state. There aren't two particles; there's a system, and that system was created from 2 particles. You don't observe a particle, you observe the system. You know everything about the system from the single observation

[IgorPartola]

Ah so the first use case is out then. Thanks for the correction.

[monadic3]

It does not help with time sync at all; you can't detect a collapse, just trigger it.