How Do You Determine if an Operator is Unitary, Hermitian, or a Projector?

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SUMMARY

The operator A defined as A = |Φ2><Φ2| + |Φ3><Φ3| - i|Φ1><Φ2| - |Φ1><Φ3| + i|Φ2><Φ1| - |Φ3><Φ1| is determined to be neither unitary nor Hermitian, as it fails the conditions AA† = I and A† = A, respectively. The operator must be shown to satisfy A² = A to confirm it as a projector. Additionally, the complex conjugation operator Cα(x) = α*(x) requires understanding eigenvalues and eigenfunctions in the context of complex functions.

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Homework Statement


Hi, so I have been given the following operator in terms of 3 orthonormal states |Φi>

A = |Φ2><Φ2| + |Φ3><Φ3| - i|Φ1><Φ2| - |Φ1><Φ3| + i|Φ2><Φ1| - |Φ3><Φ1|
So I need to determine whether A is unitary and/or Hermitian and/or a projector and then calculate the eigenvalues and eigenfunctions in the |Φi> basis.

The second question is to find eigenvalues and eigenfunctions of the complex conjugation operator acting on complex functions, Cα(x) = α*(x)

Homework Equations

The Attempt at a Solution


So for the first one I said it is an operator because, it cannot be unitary since AAτ ≠ unit matrix and not hermitian since A ≠ A, but now I fail to show A2 = A in order to prove that it is actually a projector. please help if there is an easier way.

The second part of the question am just failing to use that A in the formula A|Φi> = a|Φi> to find the eigenvalues and eigenfunctions.

The second question I don't know where to even start.
Please help, thank you very much.
 
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MrRobot said:
but now I fail to show A2 = A in order to prove that it is actually a projector. please help if there is an easier way.
Please provide your actual attempt.

MrRobot said:
The second question I don't know where to even start.
What is the definition of an eigenfunction? How does complex conjugation act on a general complex function?
 

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