Floquet theory of spin dynamics under circularly polarized light pulses

TL;DR

This paper applies Floquet theory to analyze how circularly polarized light pulses induce spin polarization and magnetization in quantum systems, revealing a two-stage process involving spin splitting and photon emission.

Contribution

It introduces a detailed Floquet-based model for spin dynamics under circularly polarized pulses, highlighting the mechanisms of spin splitting and polarization.

Findings

Field lifts spin degeneracy

Photon emission occurs at splitting frequency

Pulse induces measurable magnetization

Abstract

Within the Floquet theory of periodically driven quantum systems, the nonlinear single-spin dynamics under pulse of a circularly polarized electromagnetic field is analyzed. It is demonstrated that the field, first, lifts the spin degeneracy and, second, the field-induced spin splitting is accompanied by the photon emission at the spitting frequency. This two-stage process leads, particularly, to the polarization of spins along angular momentum of the circularly polarized field. As a result, the pulse-induced magnetization appears, what can be observed in state-of the-art measurements.