How can or why can't quantum entanglement (aka spooky action at a distance) be used for communication?

Answer 1

It does appear that, under the correct conditions, an entangled pair are capable of 'instantaneous' communication when they each collapse to their conjugate eigenstates. But it may also be the case that there's something else (like a hidden variable) going on that determines in which way they'll collapse.

But the real problem (assuming, for the moment, that they actually *do* communicate 'instantaneously') is simply this: How do you 'force' one of them to assume a particular eigenstate at the 'transmitting' end? (That is, how do you 'modulate' the communication?)


Doug

Answer 2

Because most of the ways that you might measure the behavior of the receiving particle destroy the entanglement (or gets it entangled with a bunch of other things, making the entanglement appear broken...no one really knows).

And, as far as i know, entanglement has only been accomplished with photons, which are quite useless in terms of making parts for a communication apparatus of the type that you imagine.

Answer 3

Its of no particular value as a means of communication - it is no faster than other techniques, and technically far more complex.

Its big advantage is in transmitting security information. This is because tampering with a quantum entangled signal is impossible to conceal, so you could be sure your transmission had not been intercepted. It would not necessarily be more secure - this depends on cryptography.

Answer 4

I don't exactly know -I've read several descriptions of this and I still have to doubt it.

I know one way is to think of the material in the distance covered as one big quantum system, where in effect every point is tied together by probability. Therefore, there is no time-delay as the speed of light that takes place. However, now I'm going to go re-read some stuff and see if it makes sense!

Answer 5

Because it's a secure channel between the entangled particles.

Answer 6

Because the Star Trek script people haven't decided how it will work yet.