The Science of Science Fiction: Entangled Diamonds

(Warning: technical blog post ahead. Not to be read before your morning dose of caffeine.)

According to this article on CNN, scientists have succeeded in entangling two diamonds...or have they?

If you'll pardon me using Wikipedia as a source, quantum entanglement occurs when two particles interact, sync up in at least one quantum state (like spin or polarization), and then separate. Their quantum states are still linked, so if you interact with one particle, the other one changes its quantum state instantaneously, no matter how far apart they are.

In the CNN article, which is based off a paper in Science, two diamonds were placed about six inches apart, and then photons were shot through a beam splitter. Some of these photons managed to go in two directions at once (which I think has something to do with Heisenberg's uncertainty principle, which limits how well you can know both the position and momentum of a particle at the same time). These photons caused vibrations in both diamonds at once. When the beams are recombined after they leave the diamonds, the head scientist describes it as "We know that one diamond is vibrating, but we don't know which one....In fact, the universe doesn't know which diamond is vibrating – the diamonds are entangled, with one vibration shared between them, even though they are separated in space."

I'm no quantum physicist (I just read popular books about it when I was younger), but to me, this doesn't sound like quantum entanglement. Are the diamonds still linked after the experiment ends? Does changing one diamond affect the other one, even if they're not touching? Perhaps the scientists understand this better than I do. It does seem to be linked to Bell's Theorem, but I'm not going to attempt to discuss that!

What does this experiment mean for science fiction writers? It does show that quantum effects carry over into the macroscopic world. (When I was learning about the uncertainty principle at school, we always used to say that an object like a chair does have uncertainty, but it's extremely small.) This could have implications for quantum computers and possibly speed up communication. The CNN article ends with the scientists pointing out, "This particular research project does not have any immediate technological applications. It's just really fascinating, and really confusing, at the same time." But if experiments like this one change the way we understand the universe, that's also fodder for speculative fiction.