1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Entangled Frankenstein Photons

  1. Jun 5, 2010 #1

    DrChinese

    User Avatar
    Science Advisor
    Gold Member

    Entangled “Frankenstein” Photons

    Entangled "Frankenstein" Photons
    David R. Schneider (David@DrChinese.com)

    Abstract: The H> and V> outputs of a Polarizing Beam Splitter can be combined to restore the original input superposition state, as long as no knowledge is obtained regarding the path taken through the PBS. Using this principle, it should be possible to create entangled photons from the identical H> and V> components of different polarization entangled photons. These "Frankenstein" photons will also be polarization entangled and should violate a Bell Inequality.

    -----------------------------------------------------

    Here is a link to the paper, which has too many formulae/diagrams to properly include within this post:

    http://www.drchinese.com/David/EntangledFrankensteinPhotonsA.pdf

    It is attached as well. Also attached are the key diagrams which give a pretty good idea of the proposed setup.

    Author comments for submission per IR guidelines: This work does not go against any existing experiment or generally accepted result. It extends existing application of theory with a proposed experiment to confirm or deny the central hypothesis. The hypothesis itself is an extension of an idea proposed by J.H. Eberly [7]. Full references are below.

    This work is relevant because it addresses yet another aspect of local realism: is the wave function fundamental? The local realistic side would assert that a probability amplitude is not real, but is an artifact of our lack of knowledge of the quantum world. And yet, experiment after experiment demonstrates unusual and counterintuitive elements: Entanglement of photons that have never interacted, hyperentanglement, etc. In fact, the very existence of entanglement (and superpositions) is a counter-example to local realism.

    This paper proposes that it is possible to create photons (Chris and Dale) which are themselves superpositions of 2 other photons (Alice and Bob) - and yet are properly neither alone. Such superposition is demonstrated by observation of a Bell state, signaling entanglement. The novel element is the combination of wave state of different photons. As far as I am aware, there is little in the literature regarding the interaction of wave components from different photons.

    ------------------------------------------------------

    References:
    1. G. Weihs, T. Jennewein, C. Simon, H. Weinfurter and A. Zeilinger: Violation of Bell's inequality under strict Einstein locality conditions (1998).
    2. T. Jennewein, G. Weihs, J. Pan, A. Zeilinger, Experimental Nonlocality Proof of Quantum Teleportation and Entanglement Swapping (2002).
    3. M. Eibl, S. Gaertner, M. Bourennane, C. Kurtsiefer, M. Zukowski, H. Weinfurter: Experimental observation of four-photon entanglement from down-conversion (2003).
    4. J. Barreiro: Hyper-entangled photons (2005); X. Ma, A. Qarry, J. Kofler, T. Jennewein, A. Zeilinger, Experimental violation of a Bell inequality with two different degrees of freedom of entangled particle pairs (2009).
    5. R. Kaltenbaek, R. Prevedel, M. Aspelmeyer, A. Zeilinger, High-fidelity entanglement swapping with fully independent sources (2008).
    6. A.P. French and E.F. Taylor, An Introduction to Quantum Mechanics (1979).
    7. J.H. Eberly, Bell inequalities and quantum mechanics (2001).
    8. C. Thiel, R. Wiegner, J. von Zanthier, G. S. Agarwal, Non-locality from N > 2 Independent
    Single Photon Emitters (2010).
     

    Attached Files:

  2. jcsd
  3. Jun 22, 2010 #2

    DrChinese

    User Avatar
    Science Advisor
    Gold Member

    Re: Entangled “Frankenstein” Photons

    Hey all, would like to invite your comments on the above. I have received some feedback to the effect that what I am describing is not novel. Yet I actually haven't seen a configuration like what I describe previously. The "unique" element intended from my setup is that the photons Chris and Dale are entangled, a situation that could not arise unless they are composed of wave components from two different photons (entangled Alice and Bob).

    As best as I know (which is not particularly convincing), no other experiment has demonstrated such a combination. There is the following test of Hardy's Paradox:

    Direct observation of Hardy's paradox by joint weak measurement with an entangled photon pair, Yokota et al (2009)
    http://iopscience.iop.org/1367-2630/11/3/033011/fulltext

    This setup too has Alice and Bob being split and recombined. However, it is not clear (to me anyway) that the final result detected is a combination of two different photons. Any thoughts?
     
  4. Jun 22, 2010 #3
    Re: Entangled “Frankenstein” Photons

    You make a good case for this via Zeilinger. Given the rise of Decoherence, it would seem that this is a natural extension to one more measurable set. Why not have 8, or 16? I suspect the problem is stabilizing and measuring this sample, not a lack of understanding of the quantum world. This seems to be a step up from a "resolution" of 2x2 to 4x4, to be a bit fanciful.

    I can only think of arguments against Bell being useful in denying what seems like a logical property of entangled states. This is clear support of a non-local, non-realistic (as defined by EPR) view, and as that has been the clear arc of Quantum Mechanics in the formalism and viable IMHO interpretations, I find this easy to accept; easy to accept, but difficult to grasp in terms of what this means for what reality is or isn't. Just what ARE we experiencing on a day to day basis, and what role does scale play when moving from the traditionally quantum to the classical? This feels like a step to nailing the coffin of there being a divide shut a bit more.
     
  5. Jun 22, 2010 #4
    Re: Entangled “Frankenstein” Photons

    Wouldn't it be easier and more conclusive to put a bacteria in a superposition of states by isolating it from the environment and keep it a low temperature so that which-path information by the emission of thermal radiation could not be retrieved and hence interference destroyed? Since a living functional bacteria can disappear and re-appear when the temperature goes up, it's clear what this experiment would say about the locally-realistic objects in time and space.
     
    Last edited: Jun 22, 2010
  6. Jun 22, 2010 #5
    Re: Entangled “Frankenstein” Photons

    Eventually that would be fantastic, but I think it is a ways off. In the meantime we have to work with less dynamic systems. I'm not sure that the superposition of "there and not-there" could be the case. Perhaps an activation or non-activation of a gene, or some kind of vibration/oscillation?
     
  7. Jun 29, 2010 #6

    DevilsAvocado

    User Avatar
    Gold Member

    Re: Entangled “Frankenstein” Photons

    I have been thinking... (since I’m somewhat 'guilty' :wink:)

    You know these things much better than me, and maybe this is not an 'issue', but what’s 'troubling' me is the fact the there’s one process creating the entanglement with a BBO crystal:

    photons.jpg

    Then you perform a measurement at first PBS, but not 'reading' the value.

    I’m just guessing here; but to me it looks like the wavefunction is decohered/collapsed after the first PBS... right?

    If so, are you really sure that the second PBS can 'reinstall' the shared wavefunction and superposition state... (that normally takes a BBO to create)?

    I’m mumbling here... what I wanna say is – has the theory and work of French and Taylor + Eberly been tested physically?
     
  8. Jun 30, 2010 #7

    DrChinese

    User Avatar
    Science Advisor
    Gold Member

    Re: Entangled “Frankenstein” Photons

    As far as I know, it has not been tested in that form. There have been a number of experiments in which observations have been erased. So this is conceptually in line with that. As far as I know, there have been no experiments in which the final result is a superposition of parts of different photons. For example, in the diagram you have above: the overlapped area means that you have a superposition of particles. But neither particle has had to go through a polarization measurement. In fact, the bottom ring is known H> and the top is known V> (or vice versa). But in my version, each particle is "split" before the final superposition is created.

    So I hope that makes it interesting and unique. :smile:
     
  9. Jun 30, 2010 #8
    Re: Entangled “Frankenstein” Photons

    Is there a barrier to performing this experiment? I'd love to see it done, and see what the results are in a physical setting.
     
  10. Jun 30, 2010 #9
    Re: Entangled “Frankenstein” Photons

    My gut tells me that the Frankenstein photons can decohere under the right conditions while Alice or Bob never would.
     
  11. Jul 3, 2010 #10

    DrChinese

    User Avatar
    Science Advisor
    Gold Member

    Re: Entangled “Frankenstein” Photons

    In this form, I think it should be possible to perform. You would need to adjust the path lengths precisely, but the rest of the apparatus is straightforward. I think an interferometer would be used to make the needed adjustments. I do believe this version would be easier than the Eberly version.
     
  12. Jan 7, 2011 #11
    Re: Entangled “Frankenstein” Photons

    Just out of curiosity, is there any reason that the left hand rings are, from center, red, green, blue, whereas the right hand is, from center, blue, green, red. ??
     
  13. Feb 6, 2011 #12

    DrChinese

    User Avatar
    Science Advisor
    Gold Member

    Re: Entangled “Frankenstein” Photons

    Yes, that would be an indication that there is conservation. A little more dispersion on one side is related to a little less on the other.
     
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook