Delayed choice quantum eraser – Yoon Vs Walborn experiment/paper

  1. Delayed choice quantum eraser – Yoon Vs Walborn experiment/paper

    is it true that in the Walborn experiment we manipulate p, but in Yoon paper we do not?

    The below link discusses the Walborn paper:
    http://grad.physics.sunysb.edu/~amarch/


    [​IMG]

    s = s-photon, p = p-photon
    s-photon is going down and detected by detector Ds
    p-photon is going up and detected by detector Dp
    The delay (path length) for p is such that s is detected at Ds well before p reaches the polarizer.
    Case 1:
    The polarizer/eraser is kept there and the experiment is repeated same way for say a million photons (sent one by one)
    Case 2:
    The polarizer/eraser is removed AFTER s is detected at Ds (and before p reaches the polarizer) and the same sequence of events is repeated same way for say a million photons (sent one by one)

    Questions:
    a) Will the pattern in case 1 (after correlating the entangled pairs and removing noise) be that of an interference pattern?
    b) Will the pattern in case 2 1 (after correlating the entangled pairs and removing noise) be that of a non- interference pattern?


    c) In case 2 (or even case 1) when s arrives
    a. its position is marked? On the screen of Ds
    b. However we do not know which one is the real s till we correlate with p? (i.e. remove noise)
    c. Why can we not figure out s simply via timing (velocity, distance, time calculation), without having to correlate with p?

    d) Case 2 is interesting because this is different from the experiment by Yoon where we do not mess with p?
    Yoon paper is discussed on http://en.wikipedia.org/wiki/Delayed_choice_quantum_eraser

    In the Yoon paper the path of p is not “controlled” ….hence when s strikes Ds, one could conclude that the path of p has been fixed (probabilistically) at the time struck Ds.

    However the Walborn paper is different -- where we still play with P (after s has struck Ds) by keeping or removing the polarizer/eraser.

    Thus

    Yoon-kim = DCQE with p allowed to follow whatever path it will take
    Walborn = DCQE with manipulation of p?

    Yoon = one could still conclude that once s is detected, the path of p is fixed ("probabilistically")
    Walborn = we are "operating" on p after s is detected, thus s that has happened in the past is showing results that correlate with p that is (being manipulated) in future?
     
    Last edited: May 17, 2011
  2. jcsd
  3. The answer might be that you cannot really control the randomness of the quantum/photon.
     
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