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Homework Help: Stern-Gerlach problems

  1. Oct 7, 2007 #1
    1. The problem statement, all variables and given/known data

    We're learning some basic quantum mechanics by studying the stern-gerlach experiment so some of my terminology might be a bit off as it might be particular to this book, I'm not sure.

    Say we have +z atoms (magnetic moment in +z direction?) shot through a +x selector followed by a -z selector. I need to find the probability that the atoms pass through.

    Should I get probabilities 1/2 * 0 = 0. So 0 percent make it out?

    What happened to that latex guide on here btw? I don't know how to make bras or kets or up/down arrows.
    Last edited: Oct 7, 2007
  2. jcsd
  3. Oct 7, 2007 #2


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    What's the initial state of the system ? Then what happens to it afterwards ?
  4. Oct 7, 2007 #3
    The initial state would be [tex]|\uparrow_z>[/tex]

    Then there is an +x selection measurement so wouldn't 50% get filtered out?

    Then the -z selector would block the 50% from the first measurement?
  5. Oct 8, 2007 #4


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    No. After the x selector, the atoms are polarized in the x direction, but this means that half of those left will pass the z selector and be polarized in the z direction.
    QM spin works like that.
  6. Oct 8, 2007 #5
    So 50% of the +z atoms would get selected in the +x selection and be polarized in +x. Then another 50% of those +x atoms will get slected in the -z selector? Which means 25% would make it through in total?
  7. Oct 8, 2007 #6
    Can anyone verify this reasoning?
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