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I Observing Quantum States

  1. Aug 15, 2016 #1
    Here is an interesting article off of phys.org that I really liked.


    What I found interesting is its premise of visually capturing multiple quantum states so that one could personally inspect a lot of these issues that many people are curious about: exclusion, entanglement, etc etc.

    I think it really fuels the imagination this experiment.
  2. jcsd
  3. Aug 19, 2016 #2


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    As someone who has done research into this, I'll point out that what's particularly neat about this paper is that they use a camera capable of single-photon sensitivity (which is a new technology).

    Before this, single-photon detectors have been around for decades, and similar experiments have been done, but a single-photon detector has no spatial resolution (it clicks is something hits it, and doesn't otherwise), so gathering information about entanglement correlations was a lot more labor intensive.
  4. Aug 19, 2016 #3


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    Cool, really really cool.

    I am of a more theoretical bent along the lines of Landau who I greatly admire, but that is way cool.

  5. Aug 20, 2016 #4


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  6. Aug 22, 2016 #5
    Thanks vanhees for the link (busy these days, so can use all the help I can get).

    Have a guilty secret I have to admit when I first read the article/paper, was that I was hoping they were going to announce something like seeing a particle's position and momentum at the same time or something. (snickers a bit in his sleeve). Sorry just how my mind works.

    BTW @ jfixxix, how does a single photon cam pixel actually work, I mean the operative principle? No complex equations please but just the jist behind it.
  7. Aug 23, 2016 #6


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    The basic technology is called an EMCCD array (electron multiplying charge coupled device), if you want to look it up.
    It's basically just an array of many tiny single-photon detectors arranged as a screen.

    I'm no expert on it, but I think it works like a lot of other single photon detectors.
    It's a variation of the photoelectric effect, where a single photon of sufficient energy striking a material can excite an electron into the conduction band, which is a band of energy levels in solids where electrons can flow freely.
    If you put a rather large electric voltage across this material, then when the single electron gets excited, it's accelerated by the voltage to the point where it has enough energy to smack into a bunch of other electrons, giving them enough energy to be in the conduction band too. Then that bunch of electrons is accelerated further, crashing into more and more electrons until you end up having an electric current large enough to be detected by regular equipment.

    If you're interested, you'll also want to look up the photomultiplier tube (the first widely used single photon detectors), and the avalanche photo-diode (the most popular photon detector used nowadays).
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