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Effect of photon detection mid-way between (double) slit and screen

  1. Feb 27, 2013 #1
    In a single particle double slit (self-interference) experiment:

    the which-way information is got by having the detection instrument (or at-least part of the instrumentation) right next to the slits.

    To make it easier, Let's assume the following x-coordinates:

    at source of photon x = 0
    slits are at say x = 10
    the final screen (i.e. where the pattern is formed) is at, say, x = 20

    The question is:

    1. can we detect the photon at x = 15? (i.e. somewhere between the slits and the screen)

    if so,

    2. would it's location (i.e y-coordinates at x =15) be consistent with self-interference of the wave function? i.e. show an interference pattern at x = 15? and if we were to let it proceed further (after detection) would it just proceed in a straight line and show a blob at x = 20?

    thus interference till the time the photon is not detected and no-interference after that for sometime.

    i hope i have been able to explain the question accurately, else I will do so in my responses
    Last edited: Feb 27, 2013
  2. jcsd
  3. Feb 27, 2013 #2


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    Staff: Mentor

    Re: effect of photon detection mid-way between (double) slit and scree

    How is this different from just putting the screen at 15 instead of 20?
  4. Feb 27, 2013 #3
    Re: effect of photon detection mid-way between (double) slit and scree

    good question.

    the detector allows the photon to carry/pass on its journey beyond 15

    the screen ends the journey of the photon..... at the screen at 15

    anyhow, i think you answered my question
    Last edited: Feb 27, 2013
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