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Difference between spin and polarisation?

  1. Dec 27, 2004 #1
    can someone explain to me the difference between spin and polarisation?? someone told me they were the same thing and now im getting confussed.

  2. jcsd
  3. Dec 27, 2004 #2


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    It's simple."Polarization" is a classical concept,u meet it when discussing any form of waves:electromagnetic,mechanical (sound waves in solids for example),thermal,gravitational.The concept of "spin" is entirely quantum.In QM it is the ratio for the spin angular momentum and is denoted by "s" and can take only integer and semiinteger values;in QFT is the dimension of the irreductible (for 0 and 1/2)/reductible (for 1,3/2,2,...) representation of the restricted Lorentz group.The connection between the two notions is realized by quantizing each classical wave:the electromagnetic->photon,the gravitational->graviton,the sound waves and the thermal waves in solids->phonon.The particles (quanta) have "spin",while the classical waves have "polarization".The photon has spin +1 and has 2 possible spin states.The electromagnetic wave has 2 possible polarization states.

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