Cavity-Modified Zeeman Effect via Spin-Polariton Formation

TL;DR

This paper investigates how strong coupling between an electronic spin system and an optical cavity modifies the traditional Zeeman effect, leading to spin-polariton formation and altered magnetic resonance signatures.

Contribution

It derives an effective spin-polariton Hamiltonian beyond the dipole approximation, revealing cavity-induced modifications to the spin Zeeman effect and g-factor.

Findings

Spin Zeeman effect is altered by cavity coupling.

Formation of spin-polariton states due to cavity and magnetic fields.

Potential implications for electron paramagnetic resonance (EPR) spectroscopy.

Abstract

We study the electronic spin Zeeman effect for an effective spin-$1/2$-system subject to both strong coupling to a low-frequency optical cavity and an external static magnetic field. Specifically, we address the interplay between the cavity magnetic field component in a cavity Zeeman interaction and the canonical spin Zeeman interaction from the perspective of an effective spin-polariton Hamiltonian. The latter is derived from the minimal coupling Pauli-Fierz Hamiltonian beyond the common dipole approximation via first-order quasi-degenerate perturbation theory. We find the spin Zeeman effect to be modified in the presence of the cavity field due to the formation of spin-polariton states, which result from an intricate interplay of cavity and external magnetic fields in our model. Spin-polariton signatures are discussed in the context of electron paramagnetic resonance (EPR) spectroscopy along with cavity-induced modifications of the electronic g-factor.