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wood
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Homework Statement
For a particle of mass m in a one-dimensional infinite square well 0 < x < a, the normalised energy eigenfunctions ψn and eigenvalues En (integer n = 1, 2, 3, ...) are
$$ \psi_n(x) =\sqrt{\frac{2}{a}} sin \left( \frac{n \pi x}{a} \right) \;$$ inside the well otherwise Ψn(x)=0
Consider a state A with wave function ΨA(x,t) which at time t = 0 is given by
$$\Psi_A(x,0) = \frac {4}{\sqrt{5a}} sin^{3}\left( \frac{\pi x}{a} \right) for\; 0<x<a\; otherwise\; 0. $$
1. Is the state A sharp or fuzzy in energy?
2. Check that ΨA(x, 0) is normalised to one particle.
3. If you think A is sharp in energy, what energy does it have? Otherwise, what are the possible results of repeated energy measurements for the state A, and with what probability do they occur?
4. What is the formula for ΨA(x,t) for all times t?
Homework Equations
The Attempt at a Solution
The only part of this question I can confidently do is 2. I have checked this and it is normalised to one particle.
Going back to 1 I am pretty sure that the state A is fuzzy in energy. To check this I think I need ΨA(x, 0) to be an eigenfunction of the K energy operator. Without doing the second derivative I can be pretty sure that function is not coming back anytime soon and is therefore not an eignefunction...
If I am on the right path I think I then need to find <E>A for part 3.
I would really appreciate it is anyone can help point me in the right direction on this.
Thanks