Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

LHV simulation for bell setup based on photon bunching

  1. Sep 13, 2006 #1


    User Avatar

    hi all, I return to post after about a year.

    one of the acknowledged loopholes in the bell experiments
    is how the coincidence circuitry behaves under what might
    be called "simultaneous H/V measurements" where H/V represent
    horizontal/vertical polarized photons at one arm. basically, if you
    have truly independent H/V detectors at each arm, you will measure
    simultaneous H/V events at one arm. how will the coincidence circuitry
    handle them? the naive approach is to just include them in the
    coincidence counts without any filtering.

    this is not an academic exercise, simultaneous H/V events at one
    arm are an actually measured phenomenon that goes under the
    name Hanbury-Brown/Twiss effect (measured by them) or also
    (as I understand it) "photon bunching".

    for a long time I wondered if one could construct an LHV (local hidden variable) theory for spin 1/2 particles & the EPRB setup based on this known loophole of photon bunching at one arm. it is certainly the case that almost none of the historical experiments directly address the possibility of photon bunching. [technically, the issue is handled in the coincidence circuitry, but none of the authors address it in their papers, including the classic Aspect experiments & many other bell type experiments]

    recently I managed to do just that, ie put together an LHV theory for the bell-type experimental setup. it uses photon bunching at each arm to violate the nonlocality measurement even though the mechanism is strictly local. all the experimental measurements match up, ie the sinusoidal variation in coincidences, the correlation parameter, rotational invariance of total coincidences, etcetera.

    here is a writeup of the code, the code, and numerical results of a run. the code is basically a monte carlo simulation. I believe this simulation violates the bell S locality parameter, although I have still yet to compute it.


    I would be interested to correspond with anyone about the model, esp on the yahoogroup on QM foundations I founded/moderate


    there are some papers out there in the literature that suggest that photon bunching could be involved/implicated in bell-type experiments & an explanation for the supposed observations of nonlocality. I will dig them up if there is some serious interest.

    I was also influenced by "nightlight" who posted some deep (and in my view compelling) analysis of photon bunching which is measured in "photon anticorrelation" experiments

  2. jcsd
  3. Sep 13, 2006 #2


    User Avatar
    Staff Emeritus
    Science Advisor
    Education Advisor

    Where are the "photon bunching" out of M.A. Rowe's experiment? If you argue that it is a different loophole, this means that even without any such photon bunching, you STILL get the identical result.

    Or what about the 3-particle GHZ experiments? Where are the photon bunching there? And how do you account for the all-or-nothing-type Kochen-Specker experiment?

  4. Sep 13, 2006 #3


    User Avatar

    alas the rowe experiment is quite an admirable and highly sophisticated
    experimental tour de force but from the pt of view of bell testing rigor, quite lackadaisical and flawed. if you read the paper carefully and ignore the [somewhat misleading] diagram, you will realize that they used a single laser to illuminate both ions, and a single detector to measure their excitation.

    but in the bell experiment, the very basic spirit is that measurements at both arms are independent!! the rowe arrangement is so far from this as to be almost laughable. if you read the paper, they basically assume the very conditions that a bell experiment is designed to test. there is a line that reads almost, "assuming that QM is valid, we can make the following simplification in the setup..." and at which point they eliminate independent measurements at both arms. how bogus.

    if rowe et al had used two lasers & two detectors, I would be far more laudatory of their experiment. imho if they hadnt billed it all as a test of bells thm, and more as a sophisticated measurement of qm properties of ions, I would have no objections. an obvious followup experiment, but rowe et al apparently have no further funding or interest in the subject. similar to the style of most researchers-- once they have done their one or two experiments to measure the cursory nonlocality violation, they lose all further interest and dismantle the hardware for something else.

    re: GHZ/Kochen Specker. has anyone done these experiments yet? again you can see that theoretically there is no analysis of the concept of photon bunching or how to detect it or rule it out in the papers on the subject.

    more specific/detailed critique on rowe et al here


    I would say, increasingly it seems to me that QM is based on the simplifying assumption of absence of photon bunching in detectors. it seems that [from studying the experimental record] absence of photon bunching is a very difficult and contrived experimental and physical situation, however. in other words, I think photon bunching is quite widespread.
  5. Sep 13, 2006 #4


    User Avatar
    Staff Emeritus
    Science Advisor
    Education Advisor

    Then may I suggest you write a rebuttal to the Rowe et al. paper using this point. When it gets published, then we can all pay closer attention to your point. Last time I checked, no one challenged its conclusion nor any parts of its result. Why don't you?

    Yes, it HAS been done. Search PRL.

    Sorry, but critique on some webpage is a dime a dozen, something that you already know. Someone could easily go into some forum and critique YOUR work, be it valid or not. This is not how physics is done, luckily.

    Have you TRIED doing any of the experiments? Or are you simply making "theoretical" comments on the nature of the experiment without having any first hand experience of doing it? How does one "study" experimental records? And don't you think that, while you're criticizing QM's "simplifying assumption", that you yourself have made a MAJOR assumption of this "photon bunching" with zero experimental backing? The same criticism can also be used towards what you just proposed, can it not?

    I would also remind you, since you already know this from your snide comment about our IR forum policy, that this is definitely a personal theory and therefore, can only be done in the IR forum. Therefore, this discussion should be done there.

  6. Sep 14, 2006 #5


    User Avatar

    hi zapperz. actually I do have a very intense desire to do a bell-type
    experiment, and have read some of the excellent recent papers that are coming out of two almost-undergraduate physics laboratories. Ive investigated some of the costs involved. have you done a bell experiment?

    I do hope to get my hands on a bell experiment setup someday, possibly thru a local university. maybe in another half decade the technology will "trickle down" as they say about economics.

    unfortunately the financial prerequisites for doing a bell type experiment are extreme. the aspect experiments I would estimate cost in the tens of thousands of dollars. recent technology with parametric down conversion brings the experiments down in price & looks very promising but are still significantly outside the realm of amateur testing.

    re snide comment on forum policy, not sure what you are referring to. I regard physicsforums as a valuable place to post & value its many highly qualified moderators including yourself.

    re the "independent research forum" on physics forums. imho its basically just a 3rd class thread ghetto. its moderator has posted a msg saying that he is busy with other projects & thats why the approved dialog is moving so slow. imho from a cursory review the policy is not actually designed to actively cultivate new theories, but in fact in applying the most friction possible in restricting them and shooting them down.

Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?

Similar Discussions: LHV simulation for bell setup based on photon bunching