• Support PF! Buy your school textbooks, materials and every day products Here!

Expectation values for a harmonic oscillator

  • #1

Homework Statement


I need to find <x>, <x2>, <p>, and <p2> for a particle in the first state of a harmonic oscillator.


Homework Equations


The harmonic oscillator in the first state is described by [tex]\psi[/tex](x)=A[tex]\alpha[/tex]1/2*x*e-[tex]\alpha[/tex]*x2/2. I'm using the definition <Q>=([tex]\int[/tex][tex]\psi[/tex]1*Q*[tex]\psi[/tex])dx where [tex]\psi[/tex]1 is the complex conjugate of [tex]\psi[/tex], and Q is the specific operator.


The Attempt at a Solution


I solved for <x>, and found it was zero. <p> I'll solve for in a similar fashion. However, for <x2> and <p2>, I am unsure of what operators I use. For the <x> operator, it is simply x, so for <x2>, would I use x2 as an operator?
(note that I the only superscripts here are the ones above e, I don't know why latex is putting all of my symbols so high
 

Answers and Replies

  • #2
kuruman
Science Advisor
Homework Helper
Insights Author
Gold Member
8,929
2,334
For the <x> operator, it is simply x, so for <x2>, would I use x2 as an operator?
Yes, that's what you should use.
 
  • #3
dx
Homework Helper
Gold Member
2,011
18
(Put the whole equation in the tex barackets instead of individual symbols)

The operator for <x²> is simply multiplication by x², so <x²> = ∫ψ*(x)x²ψ(x)dx, and <p²> is

[tex] -\int \psi^{*}(x) \hbar^2\frac{\partial^2}{\partial x^2}\psi(x) dx [/tex]
 
  • #4
ok, thank you so much guys. It's a good thing I have physics forum to at least make my new ventures into the realm of quantum mechanics a bit easier :)
 

Related Threads on Expectation values for a harmonic oscillator

Replies
16
Views
3K
Replies
2
Views
2K
Replies
1
Views
2K
Replies
4
Views
15K
Replies
8
Views
2K
Replies
16
Views
1K
Replies
2
Views
4K
Replies
12
Views
2K
Replies
1
Views
2K
Top