Chinese Physicists Measure Speed of "Spooky Action At a Distance"

Measuring the speed of spooky action is no trivial task. The method is to create a pair of entangled particle photons and separate them by a significant distance, in this case 15 km or so. The experiment involves performing a measurement on one photon and then timing how long it takes for the other photon to be influenced.

Of course, this is tricky to do with a single pair of photons because of the tiny periods of time involved and the rotation of the Earth which moves the experiment by distances that are significant over these time scales.

So the trick is to create a stream of entangled photons and to measure the spooky action continuously for 12 hours or more. If the experiment is aligned in an East-West direction, the contribution from the Earth’s rotation should drop out over that time.

Juan and co have perfected this technique by sending photons through the atmosphere from a fish farm near Qinghai Lake in the Tibetan Plateau. (We looked at their work last year when the same team smashed the distance record for teleporting photons using similar gear.)

They say the results are clear but do not measure the speed of spooky action directly. Instead, the results place a lower bound on how fast it must be. The answer is that it is at least four orders of magnitude faster than light, and may still turn out to be instantaneous, as quantum mechanics predicts.

Read more: Chinese Physicists Measure Speed of “Spooky Action At a Distance” | MIT Technology Review

About these ads