That'd actually be a different technology. Recently, there was an experiment conducted that seemed to prove FTL communication via quantum entanglement possible.
This did not happen.
IIRC, there was a recent experiment (posted on these forums, no less) where a sub-atomic particle was split, and then manipulated. What happened to one part of the divided particle seemed to happen to the other.
No idea if it was "real", though.
This is completely believable - the problem is that this, on its own, isn't useful for communication. If the end state is randomly determined, for instance, you need a classical channel between the two endpoints to actually use it for anything.
Quantum entanglement will be most useful for computation and encryption, not communication.
could you elaborate on this? I've never quite understood how quantum entanglement worked. all explanations I've read have had a "and stuff happens" part in it.
Oh, boy. A good and fair question. Let me give it a shot.
Let's say we entangle two particles. What does this mean? Well, they've both been generated from the same source, for instance, and we know that (because of the laws of the source process, maybe a particular kind of decay), one particle must have an UP spin, and the other a spin of DOWN.
Now, here's the thing: we haven't actually measured the particles yet, so we don't know
which one spins UP and which one spins DOWN. In ordinary, classical physics you might think, 'well, one's UP, and one's DOWN, and we just have to look to find out. It's like checking a snake's gender: you don't know until you look, but it's always been a male or a female.'
But in quantum mechanics -- due to the results of a lot of experiments and math -- we've come to believe that both particles actually exist in a state of quantum fuzziness, both UP and DOWN simultaneously. This state of fuzziness lasts until we measure them. When we measure one particle, we collapse the quantum waveform and find out that - wow! this particle spins UP.
It's important to note that the chances of getting UP or DOWN are 50/50. It's a random outcome, a coin flip.And from there we know that the other particle spins DOWN. It has to; spin has to be conserved.
But hang on a second. If that other particle was in a state of quantum fuzziness, and we still haven't measured it, why did its waveform collapse to DOWN? These particles aren't connected - they might even be hundreds of miles apart. Surely the other particle is still in a state of fuzz, UP/DOWN, waiting to be measured.
But no. It's definitely DOWN. We can check this experimentally. It'll always turn out to be DOWN...as if it somehow knows the other particle turned out UP. It's as if you flip a coin in one room, and every time it comes up heads, a coin flipped in another room comes up tails -- even though there's no communication between the two.
But if there's no hidden variable to be measured, how does this particle know what its distant sibling turned out to be? How does the coin know how the other coin landed?
There has to be some kind of spooky action at a distance - some sort of instantaneous, nonlocal link between the entangled particles that lasts until they're measured.
That's a really simplified explanation. I can go into more detail if you like, and also try to explain why it's completely useless for communication, but good for encryption.
