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Does frequency make sense in terms of one particle?

  1. Jul 18, 2007 #1
    Does "frequency" make sense in terms of one particle?

    Does the concept of frequency exist if we're only talking about one particle? Can a single photon carry frequency information, or is frequency related to the number/closeness of multiple particles?
  2. jcsd
  3. Jul 18, 2007 #2


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    Yes. A photon has a certain amount of energy, which manifests as its frequency.
  4. Jul 18, 2007 #3
    Frequency by definition requires 'oscillation in time' and a single photon which is either detected at certain spacetime point or not, simply cannot provide that oscillation. We can at most measure energy of a single photon.

    An ensamble of identical copies of the photon can allow measurement of frequency.
  5. Jul 18, 2007 #4
    Then how does the energy manifest itself as frequency? If an emitter is sending out 100 photons per second, wouldn't the frequency be 100hz, regardless of the energy of the photon?
  6. Jul 18, 2007 #5
    the frequency of the wave is not the frequency in which the particles are sent.

    if you measure the position of particles that are constantly being shot out from the emitter, and make a scatter plot out of it. (put a dot in the 3D space whenever one gets a measurement of the corresponding [tex](x, y, z)[/tex]) You'll see areas in which the dots are concentrated, and areas in which the dots are not so concentrated, the "wave" of the dots is the norm of the wave that you speak of. (i.e. [tex]|\Psi|^2[/tex])

    though often, finding [tex]|\Psi|^2[/tex] doesn't given you all the information about [tex]\Psi[/tex], hence you can do something like a double slit experiment to get an interference term.
    Last edited: Jul 18, 2007
  7. Jul 18, 2007 #6
    Thank you, that makes perfect sense to me!
    Last edited: Jul 18, 2007
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