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In our assignment, we were given this question:

[PLAIN]http://img685.imageshack.us/img685/4854/prob213.png [Broken]

I know that for (a), the answer is the first energy eigenstate since the measured energy corresponds to it. I'm not sure about the situation in (b), though.

Does "leaving the system alone, allowing it to evolve in the harmonic oscillator potential" mean that it returns to its original state (as given in the equation in the problem?

Or does it mean that a new state is created, following those in the harmonic oscillator potential, but with only the first energy eigenstate remaining?

I vaguely know that the act of measuring itself causes the wavefunction to collapse to a certain measurement and state, but what does the act of leaving it alone do?

I've tried to search through our reference, Introduction to Quantum Mechanics by David Griffiths, and through the Internet but so far I haven't seen material that might help me understand.

Thank you! :)

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# Homework Help: Measurement in quantum mechanics problem

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