Finding the mean-square position for quantum harmonic oscillator

In summary, to calculate the mean square position for a linear quantum harmonic oscillator, you can use the formula <x^2> = (1/2) * hbar/m * (n + 1/2) and use the recursion relation for Hermite polynomials to find the wave function. A useful link for further understanding can be found here: [insert link here]. Good luck with your calculations!
  • #1
anarchali
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Homework Statement


Hi,
Could someone give me a tip or two for how to calculate the mean square position ( <x^2>) for a linear quantum harmonic oscillator?


Homework Equations


I think I'm supposed to use the following recursion relation for Hermite polynomials:
yHv=vHv-1 + .5Hv+1

the v, v-1, and v+1 are supposed to be subscripts

Pointing me to a useful link would be equally helpful.

The Attempt at a Solution


Beenworking at this for a whiiiiiiile without much luck.
 
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  • #2




Thank you for your question. Calculating the mean square position for a linear quantum harmonic oscillator can be done using the following formula:

<x^2> = (1/2) * hbar/m * (n + 1/2)

Where hbar is the reduced Planck's constant, m is the mass of the oscillator, and n is the quantum number. This formula is derived from the energy eigenvalues of the harmonic oscillator.

In terms of using the recursion relation for Hermite polynomials, you are on the right track. The Hermite polynomials are used to calculate the wave function of the oscillator, which can then be used to find the mean square position. You can find more information and examples of this calculation in most quantum mechanics textbooks or online resources. Here is a helpful link to get you started: [insert link here].

I hope this helps. Good luck with your calculations!
 

FAQ: Finding the mean-square position for quantum harmonic oscillator

What is the definition of mean-square position for a quantum harmonic oscillator?

The mean-square position for a quantum harmonic oscillator is a measure of the average spread or dispersion of the position of the oscillator over time. It is calculated by taking the square of the position of the oscillator at each point in time, finding the average of these squares, and then taking the square root of the average.

How is the mean-square position related to the uncertainty principle?

The mean-square position is related to the uncertainty principle in that it represents one of the ways in which the principle manifests in quantum systems. The uncertainty principle states that it is impossible to know both the exact position and momentum of a particle at the same time. The mean-square position quantifies the spread of possible positions for the particle, thus reflecting the uncertainty in its position.

What are the units of mean-square position?

The units of mean-square position are determined by the units of position squared. For example, if the position is measured in meters, then the mean-square position would be measured in square meters (m2).

How does the mean-square position change as the energy of the quantum harmonic oscillator increases?

The mean-square position increases as the energy of the quantum harmonic oscillator increases. This is because as the energy increases, the amplitude of the oscillator's motion increases, leading to a larger spread of possible positions. This relationship is described by the Heisenberg uncertainty principle, which states that as the energy of a system increases, the uncertainty in its position also increases.

Can the mean-square position ever be equal to zero?

No, the mean-square position for a quantum harmonic oscillator can never be equal to zero. This is because of the Heisenberg uncertainty principle, which states that the uncertainty in the position of a system can never be reduced to zero. The mean-square position represents a measure of this uncertainty and will always have a non-zero value.

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