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Homework Help: Uncertainty for an Eigenstate

  1. Oct 14, 2015 #1
    1. The problem statement, all variables and given/known data
    Calculate ΔSx and ΔSy for an eigenstate S^z for a spin-1/2 particle. Check to see if the uncertainty relation ΔSxΔSy ≥ ħ|<Sz>|/2 is satisfied.

    2. Relevant equations

    3. The attempt at a solution
    I'm confused on where to start. As I am with most of this quantum stuff.
    From what we've done earlier in the class...
    ΔS = √(<S2> - <S>2)

    and i believe that <Sx2> = ħ2/4 = <Sy2> = <Sz2>

    but i dont know where i'm supposed to go from there.
  2. jcsd
  3. Oct 15, 2015 #2

    Simon Bridge

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    Homework Helper

    You need to work out <S> now.
    Review what is meant by "spin half".
  4. Oct 15, 2015 #3


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