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from the for-certain-values-of-massive dept.
Roman Schnabel, a physics professor at the Max Planck Institute for Gravitational Physics has published a paper in the journal Physical Review Letters outlining a plan for entangling two "massive" objects. He and his team are still working on a way to actually carry out the plan, but if successful, the group would succeed in entangling two 0.1 kg mass mirrors, which would represent a much larger example of entanglement than anything that has come before—up till now the largest objects to be entangled were of micron size.
Entanglement is of course the odd and perhaps a little eerie situation where two or more objects are connected in a way that cannot yet be explained—measuring one causes the other to be impacted instantaneously. The phenomenon was predicted back in the 1930's by Einstein, Podolsky, and Rosen. Over the years, scientists have developed ways to cause particles and then tiny objects to become entangled, but it still was not clear if a way could be found to cause objects large enough to be governed by classical physics to be entangled. In his paper, Schnabel draws up a means of achieving that goal, and notes that he believes it can be done.
http://phys.org/news/2015-08-physicist-unveils-entangling-massive.html
[Also Covered By]: http://physicsworld.com/cws/article/news/2015/aug/03/plan-for-supersized-entanglement-is-unveiled-by-physicist
[Abstract]: http://journals.aps.org/pra/abstract/10.1103/PhysRevA.92.012126
(Score: 1, Insightful) by Anonymous Coward on Thursday August 06 2015, @08:32AM
Well, to start with, you don't need to have the same number of electrons in the same mirror. The zero spin example is just that: An example. In principle you can entangle anything quantum. All you need is two separated objects that each can be in one of several distinguishable states (and there's no superselection rule that forbids superposition of those states). Then the laws of quantum mechanics tell you there must also be an entangled state. Of course that doesn't mean it is easy to prepare that state, let alone to prove that you prepared it.
The point of this experiment is that if they can prove entanglement, they showed that quantum mechanics is still valid for 0.1kg mirrors; objects that are clearly to be considered macroscopic. If they fail at it, it could be a hint that quantum mechanics indeed fails for macroscopic objects (but then, it might just mean that they failed to prepare/measure that state).
The double slit experiment definitely demonstrates the basic principles of quantum mechanics on which also entanglement rests, but it doesn't really make sense to speak about the entanglement of the particle with itself.
(Score: 2) by gnuman on Thursday August 06 2015, @02:29PM
The double slit experiment definitely demonstrates the basic principles of quantum mechanics on which also entanglement rests, but it doesn't really make sense to speak about the entanglement of the particle with itself.
Why not? Entanglement seems to be defined to be "N wave functions at D and we don't know which entity E is responsible for which wave function". So a trivial case would be N=1. In double slit we know which entity is responsible for interference, but we don't know which slit it goes through. So fractional wave function passes through each slit. So why can't it be said that "particle is entangled with itself" or "fractions of wave function entangle with other fractions of the same wave function"?
Thinking about it, it seems that entanglement is a more generalized QM state from single particle wave function. But still, I don't understand how it works.