Calculate the eigenfunctions for a spin half particle

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Homework Help Overview

The discussion revolves around calculating the eigenfunctions for a spin half particle using Pauli spin matrices. The original poster attempts to derive the eigenfunctions corresponding to the matrices for spin operators and explore their relationships through commutation.

Discussion Character

  • Exploratory, Conceptual clarification, Mathematical reasoning

Approaches and Questions Raised

  • Participants discuss the calculation of eigenvalues and eigenfunctions for the Pauli matrices, with the original poster presenting their findings and expressing uncertainty about their correctness. There is also a focus on how to demonstrate the commutation relations between the spin operators.

Discussion Status

Some participants have confirmed the correctness of the eigenfunctions derived by the original poster, noting only the need for normalization. The discussion is ongoing, with questions about how to approach the commutation aspect of the problem being raised.

Contextual Notes

Participants are navigating the constraints of the problem, particularly in relation to the requirements for demonstrating commutation between the spin operators.

borndisaster
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Homework Statement


Spin can be represented by matrices. For example, a spin half particle can be described by the following Pauli spin matrices
s_x = \frac{\hbar} {2} \begin{pmatrix} 0 & 1 \\ 1 & 0 \end{pmatrix} , s_y = \frac{\hbar} {2} \begin{pmatrix} 0 & -i \\ i & 0 \end{pmatrix} , s_z = \frac{\hbar} {2} \begin{pmatrix} 1 & 0 \\ 0 & -1 \end{pmatrix}

Calculate the corresponding eigenfunctions which we will denote as ɑ- and β-eigenfunctions corresponding to spin 1/2 particles. Further show that sj can be determined by the commutation of the other two matrices sn and sm , n,m≠j.

Homework Equations

The Attempt at a Solution


I have calculated the eigenvalues (first section of the question) of all three matrices to be ±ħ/2

I think the diagonal matrix sz has eigenfunctions |α> = (1; 0) and |β> = (0; 1)
From that I found the eigenfunctions of sx and sx to be
|x+> = |α> + |β> & |x-> = -|α> + |β> and
|y+> = -i|α> + |β> & |y-> = i|α> + |β> respectively

But I'm not entirely sure I'm correct...
 
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borndisaster said:
From that I found the eigenfunctions of sx and sx to be
|x+> = |α> + |β> & |x-> = -|α> + |β> and
|y+> = -i|α> + |β> & |y-> = i|α> + |β> respectively
Apart from normalization, these are correct.
 
Thanks @DrClaude

Any ideas as to how I show the commutation part of the question?
 
borndisaster said:
Any ideas as to how I show the commutation part of the question?
Calculate the commutator for each pair of operators and see what you get.
 

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