Is this superposition state an eigenstate of J^2 and L * S?

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Discussion Overview

The discussion revolves around whether a specific superposition state in the |l,m1;ms> basis is an eigenstate of the operators J^2 and L * S, and the determination of the corresponding eigenvalues. The scope includes theoretical aspects of quantum mechanics and operator actions on states.

Discussion Character

  • Exploratory, Technical explanation, Debate/contested

Main Points Raised

  • One participant presents a superposition state and requests assistance in demonstrating its properties as an eigenstate of J^2 and L * S.
  • Another participant inquires about the method to determine the action of the operators J^2, L^2, and S^2 on eigenstates.
  • A third participant provides a breakdown of the operator J^2 in terms of L and S, suggesting to apply it to the state vector.
  • There is a light-hearted exchange regarding notation and formatting of operators among participants.

Areas of Agreement / Disagreement

The discussion does not reach a consensus, as participants are exploring different aspects of the problem without resolving the initial query about the eigenstate properties.

Contextual Notes

Participants express uncertainty about the initial steps needed to analyze the superposition state and the application of operators, indicating potential gaps in understanding or assumptions regarding operator actions.

Who May Find This Useful

This discussion may be useful for students or researchers interested in quantum mechanics, particularly in the context of angular momentum and operator theory.

Ed Quanta
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Show that the following superposition state in the |l,m1;ms> basis:-(2/3)^1/2|1,-1;1/2> + (1/3)^1/2|1,0;-1/2> is an eigenstate of J^2 and L * S and determine the corresponding eigenvalues.

I have no clue how to start this. Any help would be appreciated.
 
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How do you determine the action of the operators
[tex]\hat{\vec{J}}^{2} ,\hat{\vec{L}}^{2},\hat{\vec{S}}^{2}[/tex]

on any eigenstate...?

Daniel.
 
First note that:

[tex]\hat{\mathbf {J}}^2=\hat{\mathbf {J}} \cdot \hat {\mathbf {J}}=(\hat{\mathbf {L}} + \hat{\mathbf {S}}) \cdot (\hat{\mathbf {L}} + \hat{\mathbf {S}}) =\hat{\mathbf {L}}^2 + \hat{\mathbf {S}}^2+2 \hat{\mathbf {L}} \cdot \hat{\mathbf {S}}[/tex]

Hit each term of your state vector with it.

edit: Bloody dexter, his LaTeX is faster than mine. :-p
 
Last edited:
I used "hats" for operators,that's a reason for envy...:wink: :-p

Daniel.

P.S.BTW,i resent the boldface notation of vectors... :-p
 
Last edited:
Nothing a quick edit can't fix. Now my operators don't have cold heads. :smile:
 

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