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

I The mechanism of entangled particles

  1. Aug 31, 2016 #1
    First let me ask this:

    Consider a pair of entangled photons fired at a respective detector after passing respective polarisation filters.

    If a photon passes a polarisation filter, is it in a superposition of having passed and not having passed?

    Is the measuring device (that detects the photon) in a superposition of having detected and not having detected? (or is it allowed to think of it that way?)
  2. jcsd
  3. Aug 31, 2016 #2

    The fundamental Schrodinger equation governing what is going on shows the measurement device being in a superposition of detection + non-detection. Where collapse occurs, to make the photon pass the filter or not, is subject to the still unsolved measurement problem.
  4. Aug 31, 2016 #3
    Sorry, I fear that what I was about to write will be seen as posing a theory.

    Last edited: Aug 31, 2016
  5. Aug 31, 2016 #4
    There is nothing that fails in that reasoning, since it is a perfectly valid interpretation that the combined mesurement results are not fixed until they are brought together and observed jointly. But there are also a bunch of other interpretations for this scenario.
  6. Sep 1, 2016 #5


    User Avatar
    Science Advisor
    Gold Member
    2017 Award

    No! If you have an ideal polarization filter it either absorbs a photon or it let's it through, and then either there is no photon left or the photon is in a particular linear-polarization state, determined by the orientation of the polarizer. It's a paradigmatic example of a von Neumann filter measurement as a state-preparation procedure.
  7. Sep 1, 2016 #6
    Ok. Since i get responses I will dare to put forward a mechanism for the purpose to determine at which points it goes erroneous:

    Suppose we have photon A and photon B. They are measured by apparati A resp. B. Now apparati A and B both become in superposition of detecting their respective photon, since the photons passed their polarisation filters. Now suppose that when the measurement outcomes (of A and B) are brought together, both A and B (apparatus) will collapse in a definite 'detected' or ''not-detected' state respectively, thereby retrocausally fixing the events at the polarisers and detectors. The correlation between photon A and B can be established at the joining of measurement outcomes by the knowledge (at this point) of the positions of the filters and the shared wavefunction of A and B (entanglement)(which, icw the positions of the filters, can generate the correlation).

    NOTE: I am not trying to put forward a theory. I am asking if the interpretation put forward is a valid one, and if not, why not! :wink:
    NOTE: I can elaborate a little, but leave it at this for the moment.
    Last edited: Sep 1, 2016
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?
Draft saved Draft deleted

Similar Discussions: The mechanism of entangled particles
  1. Entangled particles (Replies: 3)

  2. Entangled particles (Replies: 2)

  3. Entangled particles (Replies: 8)