Read the Clebsch-Gordan Coefficients?

In summary, to read the table, you need to look at the notation in the upper right corner of the last page of the given link. The big numbers represent the j_1 and j_2 values you want to couple. The CG - coeff is used to calculate the new basis by summing over the old basis. The formula for this is shown and explained, with the CG - coeff being the value looked up in the table.
  • #1
pivoxa15
2,255
1
How do you read the table?
 
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  • #2
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

[tex] | 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 [/tex]

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

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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1. What are Clebsch-Gordan coefficients?

Clebsch-Gordan coefficients are mathematical quantities used in the field of quantum mechanics to describe the coupling of two angular momenta. They are named after German mathematicians Alfred Clebsch and Paul Gordan.

2. Why are Clebsch-Gordan coefficients important?

Clebsch-Gordan coefficients are important because they allow us to determine the possible values of the total angular momentum when two angular momenta are combined. This is crucial in understanding the behavior of particles at the quantum level.

3. How are Clebsch-Gordan coefficients calculated?

Clebsch-Gordan coefficients are calculated using a specific formula that takes into account the individual quantum numbers of the two angular momenta being combined. This formula involves complex numbers and can be quite complex itself.

4. What is the significance of the Clebsch-Gordan diagram?

The Clebsch-Gordan diagram is a graphical representation of the Clebsch-Gordan coefficients. It allows us to visually see the relationships between the different quantum numbers and their corresponding coefficients. This can aid in understanding and predicting the behavior of particles in quantum systems.

5. How are Clebsch-Gordan coefficients used in real-world applications?

Clebsch-Gordan coefficients have applications in various fields, such as nuclear physics, solid state physics, and astrophysics. They are used to describe the behavior of particles and atoms, and their accurate calculation is crucial in understanding and predicting the properties of these systems. They are also used in the development of technologies, such as quantum computing and quantum cryptography.

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