How to Calculate Uncertainty for Spin-1/2 Eigenstates?

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SUMMARY

This discussion focuses on calculating the uncertainties ΔSx and ΔSy for a spin-1/2 particle in an eigenstate of Sz. The uncertainty relation ΔSxΔSy ≥ ħ||/2 must be verified. Key equations include ΔS = √( - ²) and the values for , , and , which are all ħ²/4. The discussion emphasizes the importance of using matrix and column vector representations of spin operators and eigenstates for accurate calculations.

PREREQUISITES
  • Understanding of quantum mechanics principles, specifically spin-1/2 systems.
  • Familiarity with the uncertainty principle in quantum mechanics.
  • Knowledge of matrix representations of quantum operators.
  • Ability to perform calculations involving expectation values in quantum states.
NEXT STEPS
  • Study the derivation of the uncertainty relation in quantum mechanics.
  • Learn about matrix representations of spin operators in quantum mechanics.
  • Explore the concept of expectation values in quantum states.
  • Review the EasySpin toolbox for practical applications in spin calculations.
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Students and researchers in quantum mechanics, particularly those studying spin systems, as well as educators looking for resources to teach uncertainty principles in quantum physics.

nmsurobert
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Homework Statement


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.

Homework Equations

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 don't know where I'm supposed to go from there.
 
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You need to work out <S> now.
Review what is meant by "spin half".
 

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