I Larmor precession of an electron in a magnetic field?

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how does one describe the Larmor precession of a spin 1/2 particle in a magnetic field in terms of quantum field theory?
In QFT where the electromagnetic field is mediated by virtual photons, is it possible to describe the larmor precession of an electron as a series of emission and absorption of virtual photons? how does the spin angular momentum "evolve" over a series of events? This feels like a challenging question.. I really appreciate a helpful answer thank you.
 
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An external classical field in QED is described as a coherent state. In perturbative terms it's given by the corresponding resummation of the "soft-photon ladders". For details see Weinberg, Quantum Theory of Fields, vol. 1.
 

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