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Spin in Quantum mechanics

  1. Mar 9, 2007 #1
    The spin of an electron is described by a vector psi = column vector with two entries,psi up and psi down

    Give the general expressions for the probabilities to find Sz= +or- h/2 in a measurement of S^z

    where Sz=h/2(1 0) as a matrix
    ( 0 -1)

    ii)Give the general expressions for the probabilities to find <S^z>

    culd anyone help,i cant find the general expressions for the probabilitites in my notes.
  2. jcsd
  3. Mar 10, 2007 #2

    Meir Achuz

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    Expand the given column vector in terms of pure up (1,0) and pure down (0,1)
    as u=a u(up) + b u(down).
    Then the proballiites are4 |a|^2 and |b|^2.
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