Integration with Euler angle of rotation matrixes

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Discussion Overview

The discussion revolves around the integration involving Euler angle rotation matrices, particularly in the context of quantum mechanics and coordinate transformations. Participants explore the properties of these matrices, their determinants, and implications for rotations acting on spin states.

Discussion Character

  • Technical explanation
  • Debate/contested
  • Mathematical reasoning

Main Points Raised

  • Some participants express uncertainty about how to express integrals in terms of Euler angles and the implications of their matrices.
  • Concerns are raised about the determinants of the matrices, with multiple participants noting that they appear to be zero.
  • One participant corrects their earlier claim about the Sz matrix and acknowledges that the matrices represent operators in quantum mechanics, which have specific properties such as determinant and trace.
  • There is a discussion about the non-invertibility of the rotation operators acting on spin states, with one participant explaining that certain eigenstates yield results that cannot be reversed.
  • A participant mentions having a general form of the rotation operator but struggles with integrating the derivative of the Euler angle vector.
  • Another participant, lacking knowledge in quantum mechanics, comments on their experience with coordinate transformation matrices, indicating a potential gap in understanding the quantum context.

Areas of Agreement / Disagreement

Participants express differing views on the properties of the matrices, particularly regarding their determinants and invertibility. There is no consensus on the correct approach to the integral or the implications of the matrices in the context of quantum mechanics.

Contextual Notes

Limitations include the potential misunderstanding of quantum mechanics principles by some participants and the unresolved nature of the integral involving Euler angles. The discussion reflects a mix of expertise levels, which may affect the clarity of the mathematical arguments presented.

Who May Find This Useful

Individuals interested in the mathematical aspects of quantum mechanics, particularly those dealing with rotation matrices and integrals, as well as those working on coordinate transformations in robotics.

RiceSweet
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Hello, I was struggling with solving a specific integral. I know that I can rewrite the exponential matrices and the range of the three Euler angles. However, I am not sure I should I write
Screenshot 2018-11-24 00.08.05.png
in terms those three Euler angles.

Screenshot 2018-11-24 00.10.35.png
 

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There is something fishy here. Both your matrices have determinant 0!
 
RiceSweet said:
Hello, I was struggling with solving a specific integral. I know that I can rewrite the exponential matrices and the range of the three Euler angles. However, I am not sure I should I write View attachment 234555 in terms those three Euler angles.

View attachment 234556
Sorry that I made a mistake for one of mine matrix. The matrix of Sz should like as follows
Screenshot 2018-11-30 13.39.10.png
 

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Svein said:
There is something fishy here. Both your matrices have determinant 0!
Hello, thanks for your reply. I made a mistake of Sz matrix, and I just updated the correct matrix. Those two matrices do have a determine as well as trace equal to 0 because those matrices are the matrix representation of Sz and S^2 operator of spin 1/2 1/2 system in Quantum Mechanics. The three exponential inside the integral represents the rotation.
 
So your rotations are non-invertible?
 
Svein said:
So your rotations are non-invertible?
Yes, because those rotations are acting on spins. For example, if We act this rotation operator related to Sz on an eigenstate |00>, we will get e^(0) = 1 as our result, and we can not reverse our process. Since our eigenvalue of |00> corresponding to the Sz operator is just 0.
 
Svein said:
So your rotations are non-invertible?
I have the general expansion form of the rotation operator already. The problem that I am struggling with is that I didn't know how to break down the derivative of this Euler angle vector (theta), and do the right integral.
Screenshot 2018-11-30 16.11.55.png
 

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Mathematically your expression does not make sense.

Since I never studied quantum mechanics, I cannot comment on whatever goes on backstage. I have, however, spent a couple of years working on robot arm coordinate transforms and I am therefore fully conversant with coordinate transform matrices.
 

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