Eigenvalues and eigenvectors of J.n

In summary, eigenvalues and eigenvectors are concepts in linear algebra used to study linear transformations. Eigenvalues represent the scaling factor of the eigenvector, while eigenvectors are only multiplied by a scalar and remain parallel to the original vector. J.n, or the Jordan normal form, is a way of writing a matrix that makes it easier to calculate and work with eigenvalues and eigenvectors. In science, eigenvalues and eigenvectors have various practical applications in understanding systems and solving complex problems. There are several methods for calculating eigenvalues and eigenvectors, including the Jordan decomposition method for J.n. It is possible for a matrix to have no eigenvectors if it is singular, but all square matrices have at least
  • #1
dfschick
2
0

Homework Statement


Calculate the eigenvalues and eigenvectors of the operator, J.n, where n is a unit vector characterized by the polar angles theta and phi, and J is the spin-1 angular momentum operator.


Homework Equations


Matrix representations for J^2 and J(z)


The Attempt at a Solution


I think that the first step is to develop the matrix for J.n but I'm not sure how that relates to the other matrices.
 
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  • #2
You want to use ##\hat{\vec{J}}\cdot\mathbf{\hat{n}} = \hat{J}_x n_x + \hat{J}_y n_y + \hat{J}_z n_z##.
 

1. What are eigenvalues and eigenvectors?

Eigenvalues and eigenvectors are concepts in linear algebra that are used to study linear transformations. Eigenvalues are scalar values that represent the scaling factor of the eigenvector, while eigenvectors are non-zero vectors that are only multiplied by a scalar, resulting in a new vector that is parallel to the original.

2. How are eigenvalues and eigenvectors related to J.n?

J.n, also known as the Jordan normal form, is a specific way of writing a matrix that is useful for studying its properties. The eigenvalues and eigenvectors of J.n are the same as the original matrix, but the arrangement of the matrix makes it easier to calculate and work with these values.

3. What is the significance of eigenvalues and eigenvectors in science?

Eigenvalues and eigenvectors have many practical applications in science, such as in physics, engineering, and data analysis. They are used to understand the behavior of systems, make predictions, and solve complex problems involving matrices and transformations.

4. How can one calculate the eigenvalues and eigenvectors of J.n?

There are several methods for calculating the eigenvalues and eigenvectors of a matrix, including the characteristic polynomial, the power method, and the QR algorithm. However, for J.n specifically, it is often easier to use the Jordan decomposition method, which involves finding the Jordan blocks and associated eigenvalues of the matrix.

5. Can a matrix have no eigenvectors?

Yes, it is possible for a matrix to have no eigenvectors. This occurs when the matrix is singular, meaning it is not invertible. In this case, the matrix does not have enough independent directions to have eigenvectors. However, all square matrices have at least one eigenvalue, which can be zero.

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