State/wave function after measurement?

[z00maffect]

If i already know the wave function then measure an observable what is the new wave function?

Is it just the eigenfunction of the observable corresponding to the measured value?

And does it stay in this state until something interacts with it?

 

[Avodyne]

If i already know the wave function then measure an observable what is the new wave function? Is it just the eigenfunction of the observable corresponding to the measured value?

Yes, at least according to the simplest measurement model.

And does it stay in this state until something interacts with it?

No, it evolves according the the Schrödinger equation with this state as the initial condition.

 

[z00maffect]

ahh yes of course, much thanks