Quantum Harmonic Oscillator Operator Commution

In summary, the conversation was about a mathematical question regarding the Quantum Harmonic Oscillator Operator Commutation. The questioner was stuck and asked for help. After some back and forth, it was revealed that the questioner had made a mistake in their calculation and the problem was solved.
  • #1
TupoyVolk
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Quantum Harmonic Oscillator Operator Commution (solved)

EDIT
This was solved thanks to CompuChip! The entire post is also not very interesting as it was a basic mistake :P No need to waste time

This is not homework (I am not currently in college :P), but it is a mathematical question I'm stuck and I would greatly appreciate help.

The Quantum harmonic oscillator Operator method uses:

[tex]\widehat{a}[/tex] = [tex]\sqrt{\frac{m\omega}{2\hbar}}[/tex]([tex]\widehat{x}[/tex] + [tex]\frac{i\widehat{p}}{m\omega}[/tex])
and
[tex]\widehat{a}[/tex][tex]^{+}[/tex] = [tex]\sqrt{\frac{m\omega}{2\hbar}}[/tex]([tex]\widehat{x}[/tex] - [tex]\frac{i\widehat{p}}{m\omega}[/tex])

It also says that:
[[tex]\widehat{a}[/tex],[tex]\widehat{a}[/tex][tex]^{+}[/tex]] = 1

[[tex]\widehat{a}[/tex],[tex]\widehat{a}[/tex][tex]^{+}[/tex]] = [tex]\widehat{a}[/tex][tex]\widehat{a}[/tex][tex]^{+}[/tex] - [tex]\widehat{a}[/tex][tex]^{+}[/tex][tex]\widehat{a}[/tex]

I keep ending up with 2!

Here is a "proof"
http://quantummechanics.ucsd.edu/ph130a/130_notes/node169.html
But they have simply multiplied [tex]\widehat{a}[/tex][tex]\widehat{a}[/tex][tex]^{+}[/tex]

I feel like I cannot continue(self-study) until I see how I'm wrong. Please help!
 
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  • #2
TupoyVolk said:
I keep ending up with 2!
Then you're doing something wrong :P
For us to see what exactly, you could post your calculation (either scanned or - preferably - nicely TeXed)

But they have simply multiplied [tex]\widehat{a}[/tex][tex]\widehat{a}[/tex][tex]^{+}[/tex]

I don't see where they did that. I just see them using the bilinearity of the commutator operation, i.e.
[r x, y] = r [x, y] (when r is a real number and x, y are operators - sorry, don't feel like putting hats and stuff)
[x + y, z] = [x, z] + [y, z] (where x, y, z are operators)
together with anti-symmetry ([x, y] = -[y, x]).

The proof looks really straightforward to me, can you maybe try to explain which step exactly is giving the problem?
 
  • #3
Thank you so much for the reply.:smile:
I believe I am wrong, because QM indeed works! I just "need" to see how.

What was written where this sentence is, had a very stupid mathematical mistake. :)

I cannot see where I am wrong.
 
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  • #4
Holy crap.
I see my giant fail.

For some reason I turned things into commutators that shouldn't be them.
Thank you so much!
 

FAQ: Quantum Harmonic Oscillator Operator Commution

1. What is a quantum harmonic oscillator operator?

A quantum harmonic oscillator operator is a mathematical operator used in quantum mechanics to describe the behavior of a quantum harmonic oscillator. It represents the energy and position of the oscillator and allows for the calculation of its quantum mechanical properties.

2. How does the quantum harmonic oscillator operator commute with other operators?

The quantum harmonic oscillator operator commutes with itself and with other operators that are related to the position and momentum of the oscillator, such as the position and momentum operators. However, it does not commute with operators that are related to the energy of the oscillator, such as the Hamiltonian operator.

3. What is the commutation relation for the quantum harmonic oscillator operator?

The commutation relation for the quantum harmonic oscillator operator is [a, a†] = 1, where a is the annihilation operator and a† is the creation operator. This relation represents the non-commutativity of the position and momentum operators for the quantum harmonic oscillator.

4. How is the quantum harmonic oscillator operator used in quantum mechanics?

The quantum harmonic oscillator operator is used in quantum mechanics to describe the behavior of a quantum harmonic oscillator and calculate its quantum mechanical properties, such as energy levels and wavefunctions. It is also used in the study of quantum field theory and quantum optics.

5. What is the significance of the quantum harmonic oscillator operator in physics?

The quantum harmonic oscillator operator has a wide range of applications in physics, including quantum mechanics, quantum field theory, and quantum optics. It is used to describe the behavior of many physical systems, such as atoms, molecules, and solid-state materials. It also plays a key role in understanding fundamental concepts in quantum mechanics, such as quantization and energy levels.

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