- #1
knut-o
- 17
- 0
Homework Statement
1. I got the wavefunctions:[tex]\psi _0=(\frac{m\omega }{\pi\hbar})^{\frac{1}{4}}\cdot e^{-\frac{m\omega}{2\hbar}\cdot x^2}[/tex],
and [tex]\psi _1=(\frac{m\omega }{\pi\hbar})^{\frac{1}{4}}\cdot \sqrt{\frac{2m\omega }{\hbar}}\cdot e^{-\frac{m\omega}{2\hbar}\cdot x^2}[/tex].
Also recomended by the task given to introduce two new variables:
[tex]\xi =\sqrt{\frac{m\omega }{\hbar}}\cdot x\\ \alpha=(\frac{m\omega}{\pi\hbar})^{\frac{1}{4}}[/tex]
Now, I am tolk to find <x>, <p>, <x2> and <p2>.
Homework Equations
I am informed how to find <x> and <p>:
[tex]<x>=\int _{-\inf} ^{\inf} x|\psi(x,t)|^2dx=\inf\psi*(x)\cdot \psi dx[/tex]
[tex]<p>=-i\hbar \int \psi* \cdot\frac{\partial\psi}{\partial x}dx[/tex]
I also wonder what the * stands for, it's not a normal multiplication-sign is it?
The Attempt at a Solution
What I am mostly curious about, is how do I find <x2> and <p2>?
I have also found:
[tex]\psi _0=\alpha\cdot e^{-\frac{\xi ^2}{2}}\\ \psi _1=\alpha\cdot\xi\cdot e^{-\frac{\xi ^2}{2}}[/tex].
Do I, when I calculate
[tex]<x>=\int _{-\inf} ^{\inf} x|\psi(x,t)|^2dx=\inf\psi*(x)\cdot \psi dx[/tex] get insterted for x [tex]x=\xi \cdot\sqrt{\frac{\hbar}{m\omega}}[/tex] and [tex]\frac{d\xi}{dx}=\sqrt{\frac{m\omega}{\hbar}}\Rightarrow dx=d\xi\cdot\sqrt{\frac{\hbar}{m\omega}[/tex]? Giving even more variables to work with in thei ntegratian/calculation?
And to find <x^2>, do I simply just square the function standing inside there, giving me [/tex]|\psi |^4[/tex] and the function I calculate for <p> and just square it?
I am so not getting this thing..