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Entanglement Geometry

  1. Nov 3, 2013 #1
    Has anyone considered whether particle entanglement might involve an extra-dimensional substructure of spacetime which negates the need for superluminal communication between entangled particles? If so, what characteristics would such a geometry need to instantly connect particles? Or is it more likely that the wave nature of entangled particles keeps them in contact with each other?
     
  2. jcsd
  3. Nov 3, 2013 #2

    K^2

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    Bell's inequalities exclude any hidden parameters. That includes any additional spaces or degrees of freedom.

    At any rate, entanglement is well enough understood. There is no super-luminal communication going on and causality is strictly preserved.
     
  4. Nov 3, 2013 #3

    atyy

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    See K^2's post above for sober and correct answers: there is no superluminal signalling in quantum mechanics that conveys classical information, and Bell's inequalities show that hidden variables must be nonlocal if quantum mechanics is correct. These are some pointers to more recent and speculative current work.

    Speculative work published in EPL
    http://iopscience.iop.org/0295-5075/78/3/30005/fulltext/
    http://arxiv.org/abs/quant-ph/0701002
    http://arxiv.org/abs/quant-ph/0701106

    Speculative, not peer-reviewed work
    http://arxiv.org/abs/1306.0533
    John Preskill blogged about it: http://quantumfrontiers.com/2013/06/07/entanglement-wormholes/

    More generally, it is possible to associate geometries with some forms of entanglement, but for reasons other than what you asked about. A key idea behind these is the gauge/gravity duality which is a conjecture, for which lots of evidence has been accumulated.
    http://arxiv.org/abs/hep-th/0603001
    http://arxiv.org/abs/0905.1317
    http://arxiv.org/abs/1106.1082
     
    Last edited: Nov 3, 2013
  5. Nov 4, 2013 #4
    Bells inequalities are in conflict with quantum theory as a whole and don't even allow for the traditional degrees of freedom. As for entanglement being well understood .... Didn't Feynman say that those that think they understand QM haven't really understood it (or something similar)?
     
  6. Nov 4, 2013 #5

    bhobba

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    Interestingly it seems some pretty general considerations tell us describing physical systems by generalized probability models leads to basically two choices - bog standard probability theory and QM. The difference is QM allows entanglement and probability theory doesn't:
    http://arxiv.org/pdf/0911.0695v1.pdf
    http://arxiv.org/pdf/quant-ph/0101012.pdf

    It would seem the rock bottom essence of quantum weirdness is entanglement, so if you succeed in having some kind of mechanism like extra dimensions for entanglement you pretty much have explained QM, which would be a rather tall order.

    Thanks
    Bill
     
  7. Nov 4, 2013 #6

    Demystifier

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    This is the wrongest interpretation of Bell inequalities I ever seen.
    For example, that would mean that entanglement of two spin-1/2 protons excludes the possibility that protons contain any additional degrees of freedom. Any yet we know they do - they contain quark degrees of freedom.
     
  8. Nov 4, 2013 #7

    Demystifier

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    See my post above.
     
  9. Nov 4, 2013 #8
    The answer is yes. You can find several references on line to multiple time dimensions for example. Peer reviewed journals are thin on the ground as it would appear that whilst string theorists are free to add extra dimensions at will the quantum theorists are bound by a strict code of 3 space and 1 time. I have often wondered why this might be and can only arrive at the conclusion that when you already have an infinite number in vector space why would you need any more? :rofl:
     
  10. Nov 4, 2013 #9
    As an aside, there are other ways to model entanglement without requiring wormholes, adding hidden dimensions, etc. For example:

    A Classical Framework for Nonlocality and Entanglement
    http://arxiv.org/pdf/1210.4406.pdf

    "Systemic Nonlocality" from Changing Constraints on Sub-Quantum Kinematics
    http://arxiv.org/pdf/1303.2867v1.pdf

    Brownian Entanglement
    http://arxiv.org/pdf/quant-ph/0412132v1.pdf

    A blog (I. T. Durham) discussing the topic in this thread with the interesting quote:
    Entanglement and non-local, finite geometry
    http://quantummoxie.wordpress.com/2012/11/08/entanglement-and-non-local-finite-geometry/
     
    Last edited: Nov 4, 2013
  11. Nov 4, 2013 #10
    I rest my case:wink:
     
  12. Nov 4, 2013 #11
    I like this one. You just need to translate to a random walk in vector space and you have QM!
     
  13. Jul 24, 2015 #12
    Another interesting paper on an experiment demonstrating classical entanglement. I'm not sure how accurate the author's conclusions are but interesting, nevertheless:
    Shifting the quantum-classical boundary: theory and experiment for statistically classical optical fields
    http://arxiv.org/abs/1506.01305
    https://www.osapublishing.org/optica/abstract.cfm?uri=optica-2-7-611
    http://www.sciencedaily.com/releases/2015/07/150721162455.htm
     
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