A pretty cool experiment that puts a lower bound on a speed of entanglement has been performed. The experimenters entangled photons, separated them, and then made their measurements.
Physicist Nicolas Gisin and colleagues at the University of Geneva in Switzerland split off pairs of quantum-entangled photons and sent them from the university’s campus through two fiber-optic cables to two Swiss villages located 18 kilometers apart. Thinking of the photons like traffic lights, each passed through specially designed detectors that determined what “color” they were when entering the cable and what color they appeared to be when they reached the terminus. The experiments revealed two things: First, the physical properties of the photons changed identically during their journey, just as predicted by quantum theory–when one turned “red,” so did the other. Second, there was no detectable time difference between when those changes occurred in the photons, as though an imaginary traffic controller had signaled them both.
The results show that any information connection between them would have to occur at at least 10,000 times the speed of light, which is interpreted as a pretty good indication that it’s an inherent behavior of quantum mechanics, and this “communication” isn’t actually taking place. (see also Bohm’s Bummed and the summary at Physics and Physicists)
nature news has an article entitled Physicists spooked by faster-than-light information transfer. LiveScience’s article is Spooky Physics: Signals Seem to Travel Faster Than Light. Which is really strange, because at least in the nature summary, they discuss how it isn’t evidence of superluminal communication
A second test ensured that the scientists in the two villages weren’t missing some form of communication thanks to Earth’s motion through space. According to Einstein’s theory of relativity, observers moving at high speeds can have different ‘reference frames’, so that they can potentially get different measurements of the same event. The Geneva results could possibly be explained if the two photons were communicating through a frame of reference that wasn’t readily apparent to the scientists.”
But theoretical calculations have shown that performing tests over a full spin of the globe would test all possible reference frames. The team did just that, and they got the same result in all cases.
The bottom line, says Gisin is that “there is just no time for these two photons to communicate”.
So why use a headline that says or implies that there is FTL information transfer, when the conclusion is that there isn’t?