- #1
jasonchiang97
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Homework Statement
So-called compatible observables correspond to operators which commute, i.e. [A, B] = 0, where [A, B] stands for AB − BA.
a) [3pt] Suppose Hermitian operators A and B represent two compatible observables, and all eigenvalues of A are different. Show that eigenstates of A are also eigenstates of B. Thus we can label the common eigenstates of A and B by the corresponding eigenvalues as |a',b'>
Homework Equations
[A,B] = AB-BA = 0
The Attempt at a Solution
A|a'> = a'|a'>
B|b'> = b'|b'>
Multiply A|a'> = a'|a'> by B
BA = B(a'|a'>) (1)
Since AB-BA = 0
AB = BA
I assume I can multiply by |a'> so
Multiply by |a'>
AB|a'> = BA|a'> = Ba'|a'>
I'm not sure if what I'm on the correct path but this is my attempt so far. I'm not sure how I can equate prove the question so I just tried something.
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