Find Expectation Value for 1st 2 States of Harmonic Oscillator

In summary, the expectation value for the first two states of a harmonic oscillator can be found by integrating <psi|A|psi> or using the ladder operators. The probability distributions can also give insight into the expectation value for position. The ladder operators can be used for a more mathematical approach.
  • #1
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how do you find the expectation value <x> for the 1st 2 states of a harmonic oscillator?
 
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  • #2
The expectation value of an operator A is <psi|A|psi>. If you're not familiar with Dirac's notation that means that for state 1 you'd integrate psi1 times A times psi1 over all space.

Once you start getting your hands dirty with the integrations pay attention to wether the integrand is even or odd. That will save you from a lot of useless intergration. Also the gamma function may prove to be useful.
 
  • #3
Well, they are [itex]\langle \psi_0|x|\psi_0\rangle[/itex] and [itex]\langle \psi_1|x|\psi_1\rangle[/itex] ofcourse.
You could find them either by integration or the application of the ladder operators.

However, a look at the probability distributions [itex]|\psi_0|^2[/itex] and [itex]|\psi_1|^2[/itex] should tell you immediately what the expectation value for the position is.
 
  • #4
Galileo said:
Well, they are [itex]\langle \psi_0|x|\psi_0\rangle[/itex] and [itex]\langle \psi_1|x|\psi_1\rangle[/itex] ofcourse.
You could find them either by integration or the application of the ladder operators.
However, a look at the probability distributions [itex]|\psi_0|^2[/itex] and [itex]|\psi_1|^2[/itex] should tell you immediately what the expectation value for the position is.

You can do that, but if you really want to see the math, use the ladder operators.

- harsh
 
  • #5
ladder operators? what's that?
 

FAQ: Find Expectation Value for 1st 2 States of Harmonic Oscillator

What is a harmonic oscillator?

A harmonic oscillator is a system in which the restoring force is directly proportional to the displacement from equilibrium. This results in a sinusoidal motion. Examples of harmonic oscillators include a mass attached to a spring and a pendulum.

What is an expectation value?

An expectation value is the average value of a measurable quantity in a given system. In the context of quantum mechanics, it is the average value of an observable, such as position or momentum, for a particular state of a system.

How do you find the expectation value for the first two states of a harmonic oscillator?

To find the expectation value for the first two states of a harmonic oscillator, you need to calculate the integral of the wavefunction squared multiplied by the corresponding observable. For the position operator, the integral is ∫ψ* x ψ dx, and for the momentum operator, it is ∫ψ* x ψ dx.

What is the wavefunction of a harmonic oscillator?

The wavefunction of a harmonic oscillator is a mathematical function that describes the probability of finding a particle in a particular state, such as position or momentum, in a harmonic oscillator system. It is represented by the Greek letter psi (ψ) and can be calculated using the Schrödinger equation.

Why is finding the expectation value for the first two states of a harmonic oscillator important?

Finding the expectation value for the first two states of a harmonic oscillator is important because it allows us to understand the average behavior of a particle in a harmonic oscillator system. This information can be used to make predictions about the behavior of the system and to compare it to experimental results. It also provides a way to quantify the uncertainty in the position and momentum of the particle.

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