# I When is a given state an eigenstate of a given operator?

1. Sep 19, 2016

### Kyle.Nemeth

How do I know if some given state is and eigenstate of some given operator?

2. Sep 19, 2016

### HAYAO

This is an extremely broad question. Are you talking about experiments or theory?

3. Sep 19, 2016

### Kyle.Nemeth

I am referring to theory. I may have posted this in the wrong category as well, I'm not sure. But I'm trying to prove that some given state is not an eigenstate of some given operator. I'm doing this all in Dirac notation and matrix representation. So, should I start with the eigenvalue equation and show that the given state is not an eigenvector of the operator (Again, I know the operator and the state in matrix form)?

4. Sep 20, 2016

### Staff: Mentor

Yes, although it may be easier to assume that it is and then derive the result that the eigenvalue is zero.

5. Sep 20, 2016

### Kyle.Nemeth

Thank you for the help Nugatory, much appreciated.