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Polarizing vs nonpolarizing beamsplitter qm toy problems etc

  1. Apr 21, 2005 #1


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    hi all .. I have heard of 3 semiclassicalist proponents,
    one of them the established scientist Jaynes, criticize the classic
    Grangier,Roger,Aspect (GRA) photon anticorrelation
    experiment on the grounds
    that it used a polarizing beamsplitter. actually, to be more
    specific, (rumor is, at a conference)
    Jaynes suggested to Grangier redoing the experiment with circularly
    polarized light, which has apparently never been done.

    my question: how does QM formalism handle the difference
    between a polarizing and "nonpolarizing" beamsplitter?
    how does it show up in the mathematics? how does it
    change the prediction?

    along these lines I was thinking it would be neat to develop
    a procedure similar to what is done for electronics components
    in intro EE classes & intro textbooks. in these classes, you are given all the
    laws for each circuit component & the general principles
    for writing equations for their interconnections (based roughly
    on F=ma), eg Kierkoff's law.

    & then apply it by analyzing/solving for
    the whole circuit given in diagram.
    this procedure can achieve a high degree of sophistication with
    eg links between imaginary number operations & solving
    the differential eqns for A/C circuits. the components are
    resistors, capacitors, etc.

    something similar is done in intro physics classes, with little
    toy problems of pendulums, blocks, springs, friction, etc. using F=ma,
    conservation of energy, etc

    it would be neat to see this done by someone for "toy"/"idealized"
    QM elements seen in typical QM papers.
    I have never seen this done anywhere. seems one could get quite a bit
    of mileage out of it. & also very useful/effective in teaching QM.

    (some of these diagrams may be on the web but I cant find one
    after a quick google search..maybe will post it later in thread if one
    turns up)


    [1] excellent online description of the GRA experiment by hans devries

    [2] recent undergraduate level GRA experiment, online also, by Thorn et al
    http://marcus.whitman.edu/~beckmk/QM/grangier/Thorn_ajp.pdf [Broken]



    Last edited by a moderator: May 2, 2017
  2. jcsd
  3. Apr 21, 2005 #2


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    Science Advisor
    Gold Member

    Grangier and especially Aspect have been through the ringer from the diehard Local Realist/Classicist crowd over the years. Nothing has been too minor to criticize. The fact is, there will ALWAYS be a few who reject the published results for one reason or another. However, these experiments have evolved substantially over the years and have been repeated plenty of times, always yielding the same results as Grangier and Aspect originally presented. They are as accepted as any experiment and meet scientific standards.

    Jaynes can say whatever he likes about circular polarized light, that does not change the fact that the classical viewpoint has been clearly rejected. The reason these experiements are picked on is because they shut the door on that viewpoint so tightly.

    If someone thinks there is a experiment that proves QM is wrong, well, let's see it. Grangier has indicated those experiments he feels are worth running.
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