Hermitian Matrix: Real & Imaginary Parts

In summary, the conversation discusses the properties of a complex Hermitian matrix and its real and imaginary parts. It is stated that the real part is symmetric and the imaginary part is anti-symmetric, with the diagonal elements equaling the negative of themselves. It is clarified that this means the imaginary part must be zero, leading to the conclusion that the diagonal elements of a Hermitian matrix are real numbers, not necessarily zero.
  • #1
EngWiPy
1,368
61
Hi,

Suppose that we have a complex matrix [tex]\mathbf{H}[/tex] that is Hermitian. The real part of the matrix will be symmetric, and the imaginary part of the matrix will be anti-symmetric. But what about the diagonal elements in the imaginary part? I mean we deduce that the elements in the diagonal of the imaginary part of the matrix equal the negative of themselves! What does this mean? or am I wrong?

Thanks in advance
 
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  • #2
y = - y implies y = 0 ... the diagonal elements of an hermitian matrix are real numbers.
 
  • #3
Petr Mugver said:
y = - y implies y = 0 ... the diagonal elements of an hermitian matrix are real numbers.

Are you saying that the diagonal elements of a Hermitian matrix are zero, or real and could be zero?
 
  • #4
S_David said:
Are you saying that the diagonal elements of a Hermitian matrix are zero, or real and could be zero?

He's saying that the imaginary part must be zero (for a number to be it's own conjugate). So yes he means real numbers not necessarily zero.
 
  • #5
uart said:
He's saying that the imaginary part must be zero (for a number to be it's own conjugate). So yes he means real numbers not necessarily zero.

Ok, I got it. Thanks a lot.
 

1. What is a Hermitian Matrix?

A Hermitian matrix is a square matrix that is equal to its own conjugate transpose. In other words, the matrix is equal to its own complex conjugate, with the real and imaginary parts switched.

2. What are the properties of a Hermitian Matrix?

One of the main properties of a Hermitian matrix is that all of its eigenvalues are real numbers. Additionally, all of its eigenvectors are orthogonal to each other. It also has the property that its diagonal entries are real numbers.

3. How do you find the real and imaginary parts of a Hermitian Matrix?

The real part of a Hermitian matrix is found by taking the average of the matrix and its conjugate transpose. The imaginary part is found by taking the difference between the matrix and its conjugate transpose, divided by two times the imaginary unit.

4. Can a Hermitian matrix have complex eigenvalues?

No, a Hermitian matrix can only have real eigenvalues. This is because the eigenvalues are the same for the matrix and its conjugate transpose, and the complex conjugate of a real number is itself.

5. What are some applications of Hermitian matrices?

Hermitian matrices are commonly used in quantum mechanics, specifically in the study of quantum states and operators. They are also used in signal processing, image processing, and statistics. In physics, they are used to represent physical observables such as energy and momentum.

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