Quantum Mechanics: Concepts and Applications · Problem 7.22

Identical Particles — Nouredine Zettili

Physics — Quantum Mechanics · spherical-tensors-commutation-relations

Problem

Prove the following commutation relations: (a) [Jx, [Jx, Tq(k)]]=∑q′Tq′(k)⟨k, q′∣Jx2∣k, q⟩\left[J_x,\,[J_x,\,T^{(k)}_q]\right] = \sum_{q'} T^{(k)}_{q'}\langle k,\,q'\mid J_x^2\mid k,\,q\rangle, (b) [Jx, [Jx, Tq(k)]]+[Jy, [Jy, Tq(k)]]+[Jz, [Jz, Tq(k)]]=k(k+1)ℏ2Tq(k)\left[J_x,\,[J_x,\,T^{(k)}_q]\right] + \left[J_y,\,[J_y,\,T^{(k)}_q]\right] + \left[J_z,\,[J_z,\,T^{(k)}_q]\right] = k(k+1)\hbar^2 T^{(k)}_q.

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