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Which path information for a photon reflecting from a mirror as in Feyman's QED

  1. Dec 3, 2011 #1
    I would like to know whether it is possible to determine which path information for a photon reflecting from a mirror as shown in the book QED by Feynman page 40 and 43 (or available by googling mirror reflection Feynman or similar) if photons are fired one at a time from the source (unaimed) and I use a directional photomultiplier detector aimed so that the field of view is a particular spot on the mirror (say 1mm of the mirror) eg use a long tube with the detector at one end and a small hole in the other end.
    Feynman uses summing over paths to get the result that it is most probable photons take the path where the angle of incidence equals the angle of reflection. However there is a small probability a photon could take an alternative path.
    If I aim my detector at the centre of the mirror no doubt I will observe a lot of the photons because there the angle of incidence equals the angle of reflection. However if I point my detector down at one end of the mirror (say at K) and wait a long time when I finally observe a photon can I deduce (assuming that it is overwhelmingly probable the photons travel in straight lines) that this particular photon took the path less travelled and reflected from K where the angle of incidence does not equal the angle of reflection?
     
  2. jcsd
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