Multi-photon Rabi oscillations in high spin paramagnetic impurity

TL;DR

This paper reports the observation of multi-photon Rabi oscillations in high-spin Mn$^{2+}$ impurities in MgO, revealing complex multi-frequency dynamics when the microwave field interacts strongly with the impurity's anisotropy.

Contribution

It demonstrates the experimental observation of multi-photon Rabi oscillations in high-spin impurities and develops a theoretical model explaining these phenomena.

Findings

Multiple photon Rabi oscillations observed in Mn$^{2+}$ impurities.

New multi-frequency spectrum arises at high microwave fields.

Theoretical model agrees well with experimental data.

Abstract

We report on multiple photon monochromatic quantum oscillations (Rabi oscillations) observed by pulsed EPR (Electron Paramagnetic Resonance) of Mn$^{2+}$ (S=5/2) impurities in MgO. We find that when the microwave magnetic field is similar or large than the anisotropy splitting, the Rabi oscillations have a spectrum made of many frequencies not predicted by the S=1/2 Rabi model. We show that these new frequencies come from multiple photon coherent manipulation of the multi-level spin impurity. We develop a model based on the crystal field theory and the rotating frame approximation, describing the observed phenomenon with a very good agreement.