Simple question concerning Hermitian operators

In summary, the conversation discusses the concept of self-adjoint operators and their properties, specifically in relation to the hermitian operator and wave function. The individual is seeking clarification on whether the operators switch places when not inside an inner product and requests links to proofs for further understanding. The conversation also mentions the concept of position representation and its relevance to the topic.
  • #1
Nikitin
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Hi. This might sound like a stupid question, but is it, in general, true that ##(\hat{H} \psi)^* \psi'= \psi^* \hat{H}^*\psi'##? Here ##\hat{H}## is a hermitian operator and ## \psi## a wave function.

I.e. do they switch places even when not inside an inner product? I am aware of the fact that you can move hermitian operators around inside an inner product, i.e. <H X| Y> = <X | H Y>, but I am unsure as to why you can do that. Can somebody link me to some proofs that explain all this?

thanks.

edit: fixed mistake in my question..
 
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  • #2
Nikitin said:
<H X| Y> = <X | H Y>

This is the definition of a self-adjoint operator so naturally a self-adjoint operator is going to fulfil it.

With regards to your original question, if you see the wave function simply as a function here you may be in trouble. Consider instead ##\langle \psi| H## as a linear map from the state space to complex numbers.

Writing down the inner product in position representation, you will get that the linear maps defined by multiplication with ##(H\psi)^*## and acting with ##\psi^* H^*## on any wave function before integration will give the same result (by definition of the adjoint, that H is self-adjoint gives ##H^* = H##.
 
  • #3
arghh I forgot to put a function to the right of the expression I was asking about, sorry about that. It's fixed now. Anyway:

what is position representation? I'm not sure if I follow your explanation..
 
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1. What is a Hermitian operator?

A Hermitian operator is a mathematical object used in quantum mechanics to represent physical observables, such as position, momentum, or energy. It is named after the German mathematician and physicist Charles Hermite.

2. How is a Hermitian operator different from other operators?

A Hermitian operator is unique in that its matrix representation is equal to its conjugate transpose. This property ensures that the eigenvalues of a Hermitian operator are always real numbers, making it useful for representing physical quantities in quantum mechanics.

3. What is the significance of Hermitian operators in quantum mechanics?

Hermitian operators play a crucial role in quantum mechanics as they represent observable quantities in the physical world. They also have special properties, such as being self-adjoint and having real eigenvalues, that make them useful in solving quantum mechanical problems.

4. Can any operator be a Hermitian operator?

No, not all operators can be Hermitian. In order for an operator to be Hermitian, it must satisfy the condition that its matrix representation is equal to its conjugate transpose. If this condition is not met, then the operator is not considered to be Hermitian.

5. What is the relationship between Hermitian operators and quantum mechanical measurements?

In quantum mechanics, the eigenvalues of a Hermitian operator correspond to the possible outcomes of a measurement of the corresponding observable. The eigenvectors of the operator represent the corresponding states of the system, with the magnitude of the eigenvalue representing the probability of measuring that particular state.

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