Quantum field theory treatment of magnetic effects on the spin and orbital angular momentum of a free electron

TL;DR

This paper uses quantum field theory to analyze how a classical magnetic field influences the spin and orbital angular momentum of a free electron, providing formulas and estimates relevant to spintronics and quantum biology.

Contribution

It introduces a quantum field theory framework to derive explicit formulas for magnetic effects on electron spin and OAM, including simple expressions for constant magnetic fields.

Findings

Derived formulas for spin and OAM changes due to magnetic fields

Simplified expressions for constant magnetic fields

Estimated effects for realistic electron states

Abstract

We consider in a quantum field theory framework the effects of a classical magnetic field on the spin and orbital angular momentum (OAM) of a free electron. We derive formulae for the changes in the spin and OAM due to the introduction of a general classical background field. We consider then a constant magnetic field, in which case the relevant expressions of the effects become much simpler and conversions between spin and OAM become readily apparent. An estimate of the expectation values for a realistic electron state is also given. Our findings may be of interest to researchers in spintronics and the field of quantum biology, where electron spin has been implicated on macroscopic time and energy scales.