Read the Clebsch-Gordan Coefficients?

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SUMMARY

The discussion focuses on reading the Clebsch-Gordan coefficients, specifically how to interpret the tables used in quantum mechanics. The coefficients are essential for coupling angular momentum states, represented by the notation j_1 and j_2. The formula provided illustrates how to express a new basis in terms of the old basis using these coefficients. The coefficients are derived from the inner product of the coupled states, which is crucial for understanding quantum state transformations.

PREREQUISITES
  • Understanding of quantum mechanics concepts, particularly angular momentum coupling.
  • Familiarity with Clebsch-Gordan coefficients and their significance in quantum state transformations.
  • Knowledge of quantum state notation and inner product representations.
  • Ability to interpret mathematical expressions and summations in the context of quantum physics.
NEXT STEPS
  • Study the derivation and applications of Clebsch-Gordan coefficients in quantum mechanics.
  • Explore the use of quantum state notation and its implications in angular momentum coupling.
  • Learn about the mathematical properties of inner products in Hilbert spaces.
  • Investigate the role of direct product bases in quantum state transformations.
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Students and professionals in quantum mechanics, physicists working with angular momentum, and anyone interested in the mathematical foundations of quantum state coupling.

pivoxa15
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How do you read the table?
 
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depends on how it looks like;)

have a look here:

http://www3.tsl.uu.se/thep/courses/QM/061027-exam.pdf

On the last page, in the upper right corner you have the notation.

The big numbers above each (i.e 1/2 x 1/2 ) and so on, are the j_1 and j_2 you want to couple.

This is where CG - coeff comes in:

New = sum over CG x old basis (also called Direct product basis).

i.e

| j_1 j_2 ; jm \rangle = \sum _{m_1 m_2} \langle j_1 j_2; m_1 m_2| j_1 j_2 ; m_1 m_2 \rangle | j_1 j_2 ;jm \rangle

Where j = j1 + j2
and:
\langle j_1 j_2; jm | j_1 j_2 ; m_1 m_2 \rangle

Is the CG - coeff.

So the coeff you look up in this table is the ones that enters that sum above.
 
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