Quantum harmonic potential problem

theWapiti
Messages
14
Reaction score
1

Homework Statement



Consider a particle of mass m in a harmonic potential:
gif.latex?V(x)%20%3D%20%5Cfrac%7B1%7D%7B2%7Dm%5Comega%5E2x%5E2.gif


If the particle is in the first excited state (n = 1), what is the probability of finding the
particle in the classically excluded region?

Homework Equations



gif.latex?%5Cint%5E%7B%5Cinfty%7D_%7B%5Csqrt%7B3%7D%7Dx%5E2e%5E%7B-x%5E2%7Ddx%3D0.0495.gif


7B%5Cpartial%20x%5E2%7D%20%3D%20%5Cpsi(%5Cfrac%7Bm%5E2%5Comega%5E2x%5E2-2mE%7D%7B%5Chbar%5E2%7D).gif


The Attempt at a Solution



I sub in
ga%5E2%7D%7B%5Chbar%5E2%7D%0A%5C%5C%0A%5C%5C%0A%5Cbeta%20%3D%20%5Cfrac%7B2mE%7D%7B%5Chbar%5E2%7D.gif


and get a wave function:

7B%5Cfrac%7B1%7D%7B4%7D%7D%5Csqrt%7B2%5Calpha%7Dxe%5E%7B%5Cfrac%7B-%5Calpha%20x%5E2%7D%7B2%7D%7D.gif


But I don't know how to set my bounds for the normalization integral.

I've been advised that the classical limits are:
gif.gif


But I'm still stuck.
 
Physics news on Phys.org
theWapiti - the classically excluded region is where the potential V(x) exceeds the total energy of the system, which in this case is \frac{3}{2}\hbar\omega. You need to find out how much of your wavefunction lies in this region. The integral given will probably come in useful for doing that.

[I suggest the powers that be move this thread to "Advanced Physics Homework"]
 
Thread 'Need help understanding this figure on energy levels'
This figure is from "Introduction to Quantum Mechanics" by Griffiths (3rd edition). It is available to download. It is from page 142. I am hoping the usual people on this site will give me a hand understanding what is going on in the figure. After the equation (4.50) it says "It is customary to introduce the principal quantum number, ##n##, which simply orders the allowed energies, starting with 1 for the ground state. (see the figure)" I still don't understand the figure :( Here is...
Thread 'Understanding how to "tack on" the time wiggle factor'
The last problem I posted on QM made it into advanced homework help, that is why I am putting it here. I am sorry for any hassle imposed on the moderators by myself. Part (a) is quite easy. We get $$\sigma_1 = 2\lambda, \mathbf{v}_1 = \begin{pmatrix} 0 \\ 0 \\ 1 \end{pmatrix} \sigma_2 = \lambda, \mathbf{v}_2 = \begin{pmatrix} 1/\sqrt{2} \\ 1/\sqrt{2} \\ 0 \end{pmatrix} \sigma_3 = -\lambda, \mathbf{v}_3 = \begin{pmatrix} 1/\sqrt{2} \\ -1/\sqrt{2} \\ 0 \end{pmatrix} $$ There are two ways...
Back
Top