Solving for <E^2> of a non-stationary state of the QSHO

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In summary, the conversation discusses the calculation of <E2> for a non-stationary state of the QSHO, which is represented by the wave function Ψ. The textbook answer for <E2> is 6.17 ħ2ω2, which is obtained by considering only the inside and outside terms of the integral, while the cross terms are assumed to be zero. However, the speaker points out that one of the cross terms is actually non-zero, which would result in a time-dependent and oscillating answer, contrary to the textbook answer. They question if they are missing something in their calculation.
  • #1
hnicholls
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I have the following non-stationary state of the QSHO:

Ψ =
MSP14861g00452b9i950b850000666ab1heg86823ge
[
gif&s=25.gif
gif&s=25.gif
gif&s=62.gif
e −3iωt/2 +
gif&s=62.gif
[
gif&s=49.gif
]
MSP8371000i0f8f1dc4d9600003a38cih2f043h9c3
e −5iωt/2]

where β = mω/ħ

in calculating <E2>

The answer I see in the textbook is 6.17 ħ2ω2.

This answer suggests that in calculating <E2> = Ψ*Ĥ2Ψ dx

where Ψ is composed of the above two terms Ψ1 and Ψ2 (a linear combination of E1 and E2 of the QSHO) the cross terms need to be zero to eliminate the time dependence as reflected in the answer in the textbook.

This leaves us with the inside and outside terms

Ψ12Ψ1 dx + Ψ22Ψ2 dx and calculating the sum of these inside and outside terms producing the answer in the textbook.


However, as I calculated the cross terms Ψ12Ψ2 dx is zero as it is an odd function, but Ψ22Ψ1 dx is not zero as it is an even function. This would not eliminate the time dependence and would not result in a non oscillating result as reflected in the textbook.


Am I missing something here?
 

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  • #2
Sorry part of Ψ did not load

Ψ =
upload_2017-7-13_22-17-2.png
[
upload_2017-7-13_22-20-37.png
βx
upload_2017-7-13_22-21-56.png
e −3iωt/2 +
upload_2017-7-13_22-23-56.png
[
upload_2017-7-13_22-23-37.png
]
upload_2017-7-13_22-17-30.png
e −5iωt/2]
 

What is a non-stationary state in the QSHO?

A non-stationary state in the Quantum Simple Harmonic Oscillator (QSHO) is a state that changes over time and is not an eigenstate of the Hamiltonian operator. In other words, the energy of the system is not constant and the state is not a solution to the Schrödinger equation.

How do you solve for of a non-stationary state in the QSHO?

To solve for of a non-stationary state in the QSHO, you need to use the time-dependent Schrödinger equation, which takes into account the changing energy of the system. This equation involves the Hamiltonian operator and the wave function of the system. By solving this equation, you can find the average energy of the non-stationary state.

What is the significance of solving for in the QSHO?

Solving for in the QSHO allows us to understand the behavior of non-stationary states and their changing energies. This information is crucial in predicting the behavior of quantum systems and can help us make more accurate calculations and predictions.

What are the limitations of solving for in the QSHO?

One limitation of solving for in the QSHO is that it only gives us the average energy of the system. It does not give us information about the specific energy levels or the dynamics of the system. Additionally, this method may not be applicable to all quantum systems, as it relies on the assumption that the Hamiltonian is time-independent.

Are there any real-world applications for solving of a non-stationary state in the QSHO?

Yes, there are several real-world applications for solving of a non-stationary state in the QSHO. One example is in the development of quantum computers, where understanding the behavior of non-stationary states is crucial for accurate calculations. Additionally, this type of analysis is also important in studying the behavior of atoms and molecules, which have non-stationary states due to their interactions with other particles.

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