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Shooting photons 1 per second?

  1. Oct 4, 2005 #1
    We might set up an experiment at University shooting photons one per second through slits. I think this experiment was done long ago and proved that light was a wave that was everywhere in that the photon seem to trave through both slits at the same time.

    But I read in the Halliday, Resnick and Walker textbook that we still do not know a lot about the photon. So my question is how can a machine shoot out 1 photon at a time?

    A photon is not matter so it does not have size or mass. How do we know that the machine is shooting out 1 photon if the photon itself is a mystery?

    Thanks
     
  2. jcsd
  3. Oct 4, 2005 #2

    vanesch

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    First of all, the photon is not such a big mystery (well, to some, it is :smile:). It is a relatively well-defined concept in a theory called quantum electrodynamics. So I don't know where H&R get their statement from! Maybe they just wanted to say that at the level of education they work (freshmen?) usually students don't know a lot about photons ?
    Hey, this year, the guy who wrote down the entire theoretical framework for optical photons just got the Nobel prize. And he didn't invent the theory, (which was older) he just worked out the framework for optics!

    However, to construct a machine that "sends out 1 photon per second" is going to be another piece of cake. I can think of 2 ways: sending out one photon per second ON AVERAGE (meaning, in 1000 seconds, the machine shot out about 1000 photons) is not difficult to do: take a light bulb, and calculate the thickness of the absorber needed. But the photons will arrive randomly.
    I could also think of a more pulsed source, which shoots out regularly (every second) an attenuated light pulse, but the pulse will then contain 0, 1 or 2 or 3 photons. No way to let you have exactly ONE photon exactly every second.

    cheers,
    Patrick.
     
  4. Oct 11, 2005 #3
    There are some setups in which you can control photon emission in order to produce photon on demand. May be, the mode I which this photon goes out is not so well determined. Look up microspheres, quantum dots and photon on demand. Probably you'll find it.

    Best Regards

    DaTario
     
  5. Oct 12, 2005 #4

    vanesch

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    Could you elaborate ? I've indeed vaguely read about having something like an excited atom in a cavity ready to be "triggered" but I'd like to learn more about it.
     
  6. Oct 12, 2005 #5

    Hans de Vries

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    An electrically driven single-photon emitter:
    http://www.photonics.com/spectra/tech/XQ/ASP/techid.1353/QX/read.htm
    http://www.mqc2.it/MQC204/Stevenson.pdf

    Single photon emitters from pyramidal quantum dots:
    http://nccr-qp.epfl.ch/webdav/site/nccr-qp/shared/import/migration/Project02b-3b.pdf

    Enhanced single-photon emission from a quantum dot in a micropost microcavity:
    http://www.stanford.edu/group/nqp/jv_files/papers/single_photons_APL_May03.pdf

    Quantum Dots Emit Single Photons at High Temperatures:
    http://oemagazine.com/fromTheMagazine/may04/pdf/eyeontech.pdf


    All the above, Microspheres, Quantum dots, pyramids and posts:
    http://www.its.caltech.edu/~mankei/ee150sp03/qdots.ppt


    Regards, Hans.
     
    Last edited: Oct 12, 2005
  7. Oct 12, 2005 #6

    vanesch

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    Thanks a lot ! I learned something new here.
    However, there's one thing that bugs me: how come that the pumping doesn't induce several down-up-down transitions ?
     
  8. Oct 12, 2005 #7

    Hans de Vries

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    They talk about single photons from single exitations, that is, single electron hole pairs.


    Regards, Hans

    BTW: I've just recieved my copy of "Optical Coherence and Quantum Optics"
    from Mandel and Wolf.
    http://www.amazon.com/gp/product/0521417112/103-1417335-7282252?v=glance&n=283155&s=books&v=glance

    Partly because of Glaubers Nobel price (Leonard Mandel is praised in
    the Nobel price text for carrying Glaubers work further) and partly
    because of our friend nightlight who claimed that the knowledge of
    Glaubers work was mandadory for interpreting the results of:
    "Observing the quantum behavior of light in an undergraduate laboratory"
    http://marcus.whitman.edu/~beckmk/QM/grangier/Thorn_ajp.pdf

    The latter fortunately isn't true (it wouldn't be an undergraduate
    experiment) The math used for the experiment is rather simple.
     
    Last edited: Oct 12, 2005
  9. Oct 12, 2005 #8

    vanesch

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    Yes, I understand that. What I don't understand, is why this single pair, during pumping, doesn't get excited, emits, gets excited again, emits again...
    Because the same mechanism that is responsible for the exciting should also be responsible for stimulated emission.

    It's a great book I have the impression. I read parts of it, but far from everything. I'd like to study it in detail one day...

    cheers,
    Patrick.
     
  10. Oct 12, 2005 #9

    Hans de Vries

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    It's almost 1200 pages :eek:. More a book to pick interesting topics from
    instead of working your way through from beginning to end... :smile:


    Regards, Hans
     
  11. Oct 12, 2005 #10

    vanesch

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    Yes, that's what I tried to do too, but it "builds up". You need to read quite a bit from previous chapters to even know what the next chapter is talking about. Happily, the first part is rather classical optics.
     
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