Double bar matrix element

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SUMMARY

The discussion centers on the properties of the modulus square of double matrix elements in the context of the Wigner-Eckart theorem, specifically regarding Hermitian operators. It is established that for a Hermitian operator M, the relationship ||^2 = ||^2 holds true. The participants confirm that this relationship extends to the double bar notation, leading to ||^2 = ||^2, reinforcing the symmetry in matrix elements dictated by the theorem.

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  • Understanding of the Wigner-Eckart theorem
  • Familiarity with Hermitian operators in quantum mechanics
  • Knowledge of Clebsch-Gordan coefficients
  • Basic concepts of quantum state notation
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malawi_glenn
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Is wondering if anyone knows if the modulus square of the double matrix element that arises in Wigner-Eckart theorem obeys the same "rule" as the ordinary does, if the operator is hermitian:

|<ajm|M|bj'm'>|^2 = |<bj'm'|M|ajm>|^2 if M is hermitian.

Is then :

|<aj||M||bj'>|^2 = |<bj'||M||aj>|^2 ?

---

I think it does, the Wigner-Eckart theorem states:

\langle njm|T^k_q|n'j'm'\rangle =\langle nj||T_q||n'j'\rangle C^{jm}_{kqj'm'}

where C^{jm}_{kqj} is a Clebsh gordan


So I think things will work out, are someone sure about how these things work, please tell me :)
 

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