Calculate the eigenfunctions for a spin half particle

In summary: If the commutator is zero, then the two operators commute, and if it is not zero, then they do not commute. In summary, spin can be represented by matrices, such as the Pauli spin matrices for a spin half particle. The corresponding eigenfunctions for spin 1/2 particles are denoted as ɑ- and β-eigenfunctions. It can be shown that the sj matrix can be determined by calculating the commutator of the other two matrices sn and sm, where n and m are not equal to j. To do so, one can calculate the eigenvalues for all three matrices and determine the corresponding eigenfunctions. The commutator for each pair of operators can then be calculated to determine if
  • #1
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
[tex] 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} [/tex]

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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  • #2
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.
 
  • #3
Thanks @DrClaude

Any ideas as to how I show the commutation part of the question?
 
  • #4
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.
 

FAQ: Calculate the eigenfunctions for a spin half particle

What is a spin half particle?

A spin half particle is a type of particle that has a spin of 1/2, which is a quantum mechanical property that describes the intrinsic angular momentum of a particle. This spin can have either an "up" or "down" orientation, and it is a fundamental property of all particles, including electrons and protons.

Why do we need to calculate the eigenfunctions for a spin half particle?

Calculating the eigenfunctions for a spin half particle allows us to understand its properties and behavior in quantum mechanical systems. Eigenfunctions are the possible states of a system, and by calculating them, we can determine the probability of a particle being in a specific state at any given time.

How do we calculate the eigenfunctions for a spin half particle?

To calculate the eigenfunctions for a spin half particle, we use mathematical equations and operators that represent the spin of the particle. These operators act on the wave function, which is a mathematical expression that describes the probability of finding a particle in a certain position and time.

What are some applications of calculating the eigenfunctions for a spin half particle?

Calculating the eigenfunctions for a spin half particle has various applications in quantum mechanics, including understanding the properties of particles in magnetic fields, determining the energy levels of atoms and molecules, and studying the behavior of particles in quantum computing.

Are there any limitations to calculating the eigenfunctions for a spin half particle?

Yes, there are limitations to calculating the eigenfunctions for a spin half particle. The equations and operators used to calculate eigenfunctions are only valid for systems with specific conditions, such as non-relativistic particles and a single particle system. Additionally, the calculations may become more complex for particles in higher energy states or in the presence of external fields.

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