Proof that (p + ix) operator is non-hermitian (easy)

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Discussion Overview

The discussion revolves around the non-Hermitian nature of the operator (p + ix) in quantum mechanics, focusing on the mathematical steps involved in proving this property. Participants explore the implications of Hermitian operators and the conditions under which the proof holds.

Discussion Character

  • Technical explanation
  • Mathematical reasoning
  • Debate/contested

Main Points Raised

  • One participant questions how to transition from the integral involving the momentum operator and the position operator to a specific form using the Hermitian property of p and x.
  • Another participant suggests that the Hermitian property of p and x is not necessary for the step in question, emphasizing the role of the imaginary unit i.
  • A third participant raises a concern about the notation used in the integrals, particularly regarding the treatment of complex wave functions in quantum mechanics.
  • A later reply indicates that the operator was analyzed under the Hermitian condition, leading to the conclusion that it is non-Hermitian due to the presence of the imaginary unit.

Areas of Agreement / Disagreement

Participants express differing views on the necessity of the Hermitian property for the proof, indicating that multiple competing perspectives remain. The discussion does not reach a consensus on the implications of the mathematical steps involved.

Contextual Notes

There are unresolved questions regarding the treatment of complex wave functions and the specific mathematical steps required to demonstrate the non-Hermitian nature of the operator.

halfoflessthan5
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there's one line that keeps coming up in proofs that I don't get. How do i get from

\int (\hat{p}\Psi1)*\Psi2 + i \int (\hat{x}\Psi1)\Psi2

to

\int ( (\hat{p}-i\hat{x}) \Psi1)*\Psi2

using the fact that p and x are Hermitian.

im sure its painfully simple but i can't see it.
 
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halfoflessthan5 said:
there's one line that keeps coming up in proofs that I don't get. How do i get from

\int (\hat{p}\Psi1)*\Psi2 + i \int (\hat{x}\Psi1)\Psi2
I guess you mean that there is a complex conjugate on (x Psi_1) in the second term)
to

\int ( (\hat{p}-i\hat{x}) \Psi1)*\Psi2

using the fact that p and x are Hermitian.

im sure its painfully simple but i can't see it.

Well, for that step you actually do not need at all to use the fact that x and p are hermitian.

All you need to use is that i = (-i)*
 
Why the * in the first integral, but not the second? The second integral only makes sense in QM if the wave function is real, when, in fact, most wave functions are complex.

Anyway, both p and x are Hermitian. Thus (P+iX)* =(P-iX), virtually by definition, as i is anti-Hertmitian.
Regards,
Reilly Atkinson
 
okay got it.

I put the operator into the RHS of the hermitian condition, took the complex conjugate and re-arranged it so that it was in the same form as the LHS of the hermitian condition. the inequality obviously doesn't hold because the 'i' put a minus in one, so the operator wasn't hermitian. thankyou so much guys. and sorry for the typo
 

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