Solving Eigenket Homework: Show A† Has Eigenbra <a*| to Eigenvalue a*

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Homework Help Overview

The problem involves demonstrating a relationship between an operator and its adjoint in the context of quantum mechanics, specifically regarding eigenkets and eigenbras. The original poster seeks to understand how the adjoint operator A† relates to the eigenket |a> and its corresponding eigenbra

Discussion Character

  • Exploratory, Conceptual clarification, Mathematical reasoning

Approaches and Questions Raised

  • Participants discuss taking the adjoint of both sides of the eigenvalue equation and question the implications of their manipulations. There is uncertainty about the relationship between the eigenvalue a and its complex conjugate a*.

Discussion Status

The discussion is ongoing, with participants sharing their attempts at manipulating the equations. Some guidance has been offered regarding the mathematical steps involved, but there is still confusion about the implications of certain steps and the relationship between the eigenvalues.

Contextual Notes

There is a lack of clarity regarding the assumptions about the eigenvalues, particularly whether a equals a*. Participants are also navigating the conventions of notation in quantum mechanics, which may affect their understanding.

ConeOfIce
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Homework Statement


Show that if an operator A has an eigenket |a> to eigenvalue a then
the adjoint operator A† has an eigenbra <a*| to eigenvalue a*. How
is <a*| related to |a>?


Homework Equations


A|a> = |a>a
| >† = < |


The Attempt at a Solution


I actually have no clue where to start this question. I am guessing it has something to do with A† would have an eigenket of |a>†. But I am unsure if this is correct at all.
Would anyone be able to help me get started.
 
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ConeOfIce said:

Homework Statement


Show that if an operator A has an eigenket |a> to eigenvalue a then
the adjoint operator A† has an eigenbra <a*| to eigenvalue a*. How
is <a*| related to |a>?


Homework Equations


A|a> = |a>a
| >† = < |


The Attempt at a Solution


I actually have no clue where to start this question. I am guessing it has something to do with A† would have an eigenket of |a>†. But I am unsure if this is correct at all.
Would anyone be able to help me get started.

Take the dagger of (A |a>) This must be equal to the dagger of (a |a>).
 
nrqed said:
Take the dagger of (A |a>) This must be equal to the dagger of (a |a>).

Ok, I do this. And I also took the dagge of both sides of the equation. So I got
(A|a>)^(dagger) = (|a>a)^dagger which gets

<a|A* = a*<a|.

And using your statement form above I then do
A*<a| = a|a> .
How does this get me any closer to the answer?
 
ConeOfIce said:
Ok, I do this. And I also took the dagge of both sides of the equation. So I got
(A|a>)^(dagger) = (|a>a)^dagger which gets

<a|A* = a*<a|.
So you are done! You have proved that <a| is an eigenbra of A* with eigenvalue a*!
And using your statement form above I then do
A*<a| = a|a> .
How does this get me any closer to the answer?
?:confused: What statement from above? I did not say anything lik ethat!
 

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