What happens to the wave function after an operator transformation?

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Discussion Overview

The discussion revolves around the transformation of the wave function in quantum mechanics when an operator, specifically the Hamiltonian, is transformed. Participants explore the implications of this transformation on the wave function and the eigenstates in the context of quantum systems, such as the harmonic oscillator.

Discussion Character

  • Technical explanation, Conceptual clarification, Debate/contested

Main Points Raised

  • One participant proposes that when the Hamiltonian is transformed using a unitary operator, the wave function itself may also undergo a transformation.
  • Another participant asserts that if the operator is transformed, the wave function or state remains unchanged.
  • A further inquiry is made about how the new wave function appears after the transformation, specifically in the context of the harmonic oscillator.
  • A participant mentions that there are two formal approaches in quantum mechanics regarding transformations: one where the wave function is affected and another where only the operator is affected, indicating that the transformation of the Hamiltonian does not change the wave function directly.
  • It is noted that while the wave function may not change, the eigenvalues and eigenvectors will change due to the transformation of the operator.

Areas of Agreement / Disagreement

Participants express differing views on whether the wave function is altered by the transformation of the Hamiltonian. Some argue that the wave function remains unchanged, while others suggest that it may be transformed, leading to an unresolved discussion on this point.

Contextual Notes

The discussion highlights the dependence on different formalisms in quantum mechanics and the implications of operator transformations on wave functions and eigenstates, which may not be fully resolved.

roya
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for example, if the hamiltonian of a system is transformed this way:
H(x) --> H(x+a)
i understand that the tranformation can be represented by a unitary operator U=exp(iap/[tex]\hbar[/tex])
UH(x)U[tex]^{*}[/tex]=H(x+a)

but what happens to the wave function? how is it transformed?
 
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If the operator is transformed, then the wavefunction or state is left alone.
 
what i mean to ask is how does the new wave function look like.
the harmonic oscillator for example, H=p[tex]^{2}[/tex]/2m+m[tex]\omega^{2}x^{2}[/tex]/2
if H(x) --> H(x+a) , then the eigenstates represented in the position basis must go through some sort of transformation as well.
how do i represent that transformation?
 
Last edited:
RedX answered that question. There are two formalisms in quantum mechanics. You can think of a transformation as affecting the wave function only, not the operator, or as affecting the operator only, not the wave function. since you are transforming the Hamiltonian, you are using the second formalism. The wavefunction is not changed in any way. Of course, the eigenvalues and eigenvectors will change because now they are eigenvalues and eigenvectors of this new operator.
 
thanks for the response, i think i partially understand my confusion now.had another question, but just figured it out, so thanks again.
 
Last edited:

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