Computing Eigenfunctions for a One-Dimensional Operator

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SUMMARY

The discussion focuses on computing eigenfunctions for a one-dimensional operator defined as O = p + x, where p is the momentum operator and x is the position operator. Participants explore the mathematical derivation of the eigenfunction ѱ and its normalization, emphasizing that the constants k and c are arbitrary and determined by normalization conditions. The conversation also highlights the relationship between the eigenfunctions of the position and momentum operators, concluding that the eigenfunction ѱ can represent various physical states, particularly Gaussian wavefunctions.

PREREQUISITES
  • Understanding of quantum mechanics operators, specifically momentum (p) and position (x) operators.
  • Familiarity with eigenvalues and eigenfunctions in quantum mechanics.
  • Knowledge of complex functions and their properties, including complex conjugates.
  • Ability to perform Gaussian integrals and normalization of wavefunctions.
NEXT STEPS
  • Study the derivation of eigenfunctions for the momentum operator using the equation \(\hat{p} \psi(x) = -i\hbar \frac{d}{dx} \psi(x)\).
  • Learn about normalization techniques for wavefunctions, particularly Gaussian functions.
  • Explore the concept of expectation values in quantum mechanics, specifically for position and momentum.
  • Investigate the implications of the Heisenberg Uncertainty Principle in relation to wavefunctions.
USEFUL FOR

This discussion is beneficial for students and practitioners of quantum mechanics, particularly those studying wavefunctions, eigenvalues, and operators. It is especially relevant for those seeking to deepen their understanding of one-dimensional quantum systems and Gaussian wavefunctions.

  • #31
actually, this was written in the post

<br /> &lt; x &gt; = \int _{\text{All space}} \psi^*(x)x\psi(x) dx = \int x|\psi (x)|^2 dx <br />

So I have no clue why you asked. Maybe this is too difficult for you? I suggest you wait. You still don't seem to follow my advise that taking one small step a head =(
 
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  • #32
i just didnt know the notation. i know the complex conjugate. ok, so here's the question.
for yesterdays O(with hat) i got the eigenfunction(ѱ) after normalization to be,
ѱ=exp((x2 -x)/2ih') how would i go on about finding the expectation value of x, px and px2?
would you mind telling me the process step by step??
 
  • #33
I don't think you understand this thing with operators and eigenfunction...

It is a difference of FINDING the eigenfunctions to a given operator and finding the eigenvalues of a given operator on a given wavefunction.

The example was:

Given the wavefuction \psi(x) = (1/(\pi ^{1/4}\sqrt{d}))\exp (ikx - x^2/(2d^2))

Evaluate the expectation values of x, x^2, p and p^2

------

So for the first part, <x> is int ѱ* x ѱ dx

What you need to know here are two parts, first what the complex conjugate of ѱ is and then what integral of a Gaussian integral is.

http://en.wikipedia.org/wiki/Gaussian_integral

See " Generalizations "

This is too hard for you, I give up.
 

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