A relativistic QFT description for the interaction of a spin with a magnetic field

TL;DR

This paper derives a relativistic quantum field theory framework for spin-magnetic field interactions, clarifying how non-relativistic models emerge and highlighting relativistic corrections relevant for experimental and quantum information contexts.

Contribution

It provides a full quantum field theoretical derivation of spin-magnetic interactions, including relativistic effects often neglected in simplified models.

Findings

Relativistic corrections to spin-magnetic interactions are identified.

Non-relativistic models are shown to emerge from the relativistic QFT framework.

Comparison with simplified models used in quantum information is discussed.

Abstract

We analyze how non-relativistic effective models for the magnetic coupling of a spin to the electromagnetic field (proportional to $\hat{\boldsymbol{\sigma}}\cdot \boldsymbol{B}$) emerge from a full quantum field theoretical description of charged fermionic fields with the quantum electromagnetic field. This allows us to keep track of relativistic corrections to the models commonly used in experimental spin physics. We discuss how this interaction compares to the usual simplified models used in relativistic quantum information.