"Spooky" Science Points Towards Quantum Computing

Stony Stevenson writes to tell us that University of Michigan physicists have been able to establish an "entanglement" between two atoms trapped more than a meter apart in different enclosures using light. This shows how two different atoms can have a sort of communication, something Einstein referred to as 'spooky action-at-a-distance'. "By manipulating the photons emitted from each of the two atoms and guiding them to interact along a fibre-optic thread, the researchers were able to detect the resulting photon clicks and entangle the atoms. Professor Monroe explained that the fibre-optic thread was necessary to establish entanglement of the atoms. But the fibre could be severed and the two atoms would remain entangled, even if one were 'carefully taken to Jupiter'."

Comments

"a sort of communication"

[zCyl]

We should probably not use words like "communication" to describe entanglement, because it only confuses people. Connection and correlation do not equal classical communication.

Re:Entanglement and causality?

[xtieburn]

How entanglement works though is that you have two billiard balls that are not red or blue but both simultaneously. That is unless you measure it.

So you take your boxes too each side of the world and look in one that sets that ball to say red, the other turns blue instantly, and when you say instantly you really mean it, it is faster than light, faster than what should be the infinite speed, it is instant.

That is weird.

However, your example is accurate in describing why quantum entanglement doesn't break causality. You see you can't predict what colour the ball is going to be so you can't go to one end with eight boxes and say 'right ill make this byte the number 172.' then set your balls to 10101100 leading to the other boxes instanteously being set as well.

All you can do is measure the 8 boxes find out which are red and blue at either end confirm that they are entangled, thats it. No information transfer no causality breaking.

This is also why the initial posts idea falls down. You might know which particle is entangled with which but you can't measure its status without breaking the entanglement. So you could say tell the person 'measure it in 10 minutes and see if its broken down.' and yes you confirm that the entanglement breaks down instantaneously but you rather defeat the point by already giving the information. Either that or the person can guess when it breaks down but measuring it causes it to break down and bam you defeat the point again.

Entanglement has some kind of instant effect but it can not be used to send information and thus causality is preserved.

Re:Entanglement and causality?

[QMO]

Once again, I'll quote the dude.

"Half of what we know about physics is wrong. The trouble is, we don't know which half." -Gary Skouson (AFAIK)