Are These Hermitian Conjugates Correct?

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Homework Help Overview

The discussion revolves around finding the Hermitian conjugates of various operator expressions in quantum mechanics, specifically focusing on the operators A and B. The expressions include combinations of these operators and their properties under conjugation.

Discussion Character

  • Conceptual clarification, Mathematical reasoning

Approaches and Questions Raised

  • The original poster attempts to verify the correctness of their calculations for the Hermitian conjugates of the given expressions and seeks to simplify them further. Some participants question specific steps in the calculations, particularly in point c.) and the validity of the final equality.

Discussion Status

The discussion is active, with participants providing feedback on the calculations. There is acknowledgment of a potential error in the reasoning for point c.), and some participants confirm the correctness of earlier steps while questioning later conclusions.

Contextual Notes

Participants are navigating the complexities of operator algebra and Hermitian properties, with an emphasis on ensuring the accuracy of their mathematical manipulations. There is a focus on the implications of the properties of Hermitian conjugates in the context of quantum mechanics.

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Homework Statement



Find the hermitian conjugates, where A and B are operators.

a.) AB-BA
b.) AB+BA
c.) i(AB+BA)
d.) A^\dagger A


Homework Equations



(AB)^\dagger =B^\dagger A^\dagger



The Attempt at a Solution



Are they correct and can I simplify them more?

a.) (AB-BA)^\dagger = (AB)^\dagger - (BA)^\dagger= B^\dagger A^\dagger - A^\dagger B^\dagger = BA-AB = -(AB-BA)

b.) (AB+BA)^\dagger = (AB)^\dagger + (BA)^\dagger= B^\dagger A^\dagger + A^\dagger B^\dagger = BA+AB

c.) [i(AB+BA)]^\dagger = -i[(AB)^\dagger + (BA)^\dagger]= -i(B^\dagger A^\dagger + A^\dagger B^\dagger) = BA+AB

d.) [A^\dagger A]^\dagger = A^\dagger (A^\dagger)^\dagger=A^\dagger A
 
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For point C.) -i(B^\dagger A^\dagger + A^\dagger B^\dagger)
 
Alright. The last equality is not true. That's what I meant.
 
Is it ok until -i(B^\dagger A^\dagger + A^\dagger B^\dagger)?
 

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