Seriously stuck 3D Quantum Harmonic Oscillator

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SUMMARY

The discussion revolves around solving problem 3.21 from Sakurai's 2nd edition textbook, focusing on the 3D Quantum Harmonic Oscillator. Participants are attempting to express the spherical state |01m> in terms of Cartesian eigenstates, with specific energy calculations provided. The energy in spherical coordinates is calculated as E=5/2 ħω, while the Cartesian representation is discussed through the equation E=(n_x+n_y+n_z+3/2)ħω. The challenge lies in determining the coefficients for the transformation between spherical and Cartesian bases, particularly through the computation of matrix elements.

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  • Understanding of quantum mechanics, specifically the Quantum Harmonic Oscillator.
  • Familiarity with spherical and Cartesian coordinate systems in quantum mechanics.
  • Knowledge of raising and lowering operators in quantum mechanics.
  • Ability to compute matrix elements and diagonalize operators.
NEXT STEPS
  • Learn how to compute matrix elements for quantum states using the inner product.
  • Study the process of diagonalizing operators in quantum mechanics.
  • Explore the relationship between spherical and Cartesian bases in quantum systems.
  • Investigate the properties of angular momentum operators, particularly L_z.
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Students and educators in quantum mechanics, particularly those tackling problems related to the Quantum Harmonic Oscillator and transformations between different coordinate systems.

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Homework Statement


The question is from Sakurai 2nd edition, problem 3.21. (See attachments)

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EDIT: Oops! Forgot to attach file! It should be there now..
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The Attempt at a Solution


Part a, I feel like I can do without too much of a problem, just re-write L as L=xp and then re-write x and p in terms of the raising and lowering operators. Part B is where I have no idea.

It says to write |01m> in TERMS of the eigenstates in cartesian coordinates. So I figure for q=0, l=1 the energy in spherical coordinates is..

E=\frac{5}{2}\hbar \omega

So, obtaining this energy in cartesian coordinates, we can have..

(n_x , n_y , n_z) = (1 0 0) OR (0 1 0) OR (0 0 1)

Since in the rectangular coordinate system

<br /> E=(n_x+n_y+n_z+3/2)\hbar \omega<br />

So if we were to write the spherical state in terms of the cartesian degenerate states, I would assume that would mean..

|0 1 0&gt;_S=A|1 0 0&gt;_C+B|0 1 0&gt;C + C|0 0 1&gt;_C

Where subscript C = Cartesian basis and subscript S = spherical basis.

Am I on the right track here? Because In order to find the coefficients I need to compute (for example)

A=_S&lt;1 0 0|0 1 0&gt;_C

And I am not sure how to do that!
 

Attachments

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Hi, I am actually stuck on this problem at a similar state. I was curious if you were able to find a solution or any material covering this problem.
 
Try finding the matrix that represents ##\hat{L}_z## with respect to the cartesian basis and diagonalizing it.
 

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