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The physics behind the thermal light quantum imaging?

  1. May 18, 2012 #1
    Does it indicate that the " spooky action(correlation)" even can be found in classical level, where entanglement is hardly can be built?
  2. jcsd
  3. May 19, 2012 #2


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    Thermal light ghost imaging works in a classical manner without entanglement. Correlation is there, but it is not a spooky action at all. In thermal ghost imaging you typically shine laser light through a rotating ground glass disk. This will create a diffraction pattern which varies rapidly with time. Now you send this diffraction pattern through a beam splitter and place the iimage you want to look at and a single pixel detector in one arm and the position sensitive detector in the other arm. The image will reappear in the coincidence counts between the single pixel detector and the position sensitive detector because the two beams are classically correlated without involving any spooky action. They simply are the same time-varying diffraction pattern.

    In principle it is also possible to do this kind of experiment completely without the second position sensitive detector. If you can deterministically create the time-varying diffraction pattern - for example using a digital micromirror device or a spatial light modulator - you can correlate the signal on the single-pixel camera with the pattern the other detector would have seen (you can calculate it as the diffraction pattern is created deterministically) and will find the image by doing so. If you are interested in this topic, a good overview and comparison of classical versus non-classical ghost imaging methods can be found in Jeffrey Shapiro's overview article "ghost imaging: from quantum to classical to computational" (Advances in Optics and Photonics, Vol. 2, Issue 4, pp. 405-450 (2010)).
    It is very detailed.
  4. May 19, 2012 #3
    thank u very much. I got some brief notion. I then wonder the imaging thing just give a illusion of imagining by a trick of "coincidence counts". I will squezee out sometime to have a detailed learning .
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