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

  • Thread starter Thread starter ConeOfIce
  • Start date Start date
Join the discussion
Registration is free. Ask a follow-up in this thread, or start your own.
4 replies · 4K views
ConeOfIce
Messages
13
Reaction score
0

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.
 
Physics news on Phys.org
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!