Dissipative dynamics of qubits driven by a bichromatic field in the dispersive regime

TL;DR

This paper analyzes the complex dynamics of qubits driven by bichromatic fields in the dispersive regime, revealing frequency shifts due to dynamical Zeeman and Bloch-Siegert effects, with experimental validation in pulse EPR.

Contribution

It provides an analytical description of qubit dynamics beyond the rotating wave approximation, highlighting the distinct effects of dynamical Zeeman and Bloch-Siegert shifts.

Findings

Frequency shifts caused by dynamical Zeeman and Bloch-Siegert effects.

Experimental confirmation in pulse EPR for crystalline quartz.

Dependence of effects on detuning sign.

Abstract

We study the coherent dynamics of relaxing qubits driven by a bichromatic radiation in the dispersive regime, when detuning of the frequency $\omega_{rf}$ of a longitudinal radiofrequency field from the Rabi frequency $\omega_{1}$ in a transverse microwave field is comparable in magnitude to $\omega_{rf}$ and $\omega_{1}$. We analytically describe this regime beyond the rotating wave approximation and find that the dominant feature of dynamics of qubits is the shift of the Rabi frequency caused by the dynamical Zeeman and Bloch-Siegert-like effects. These fundamental effects can be experimentally separated because, unlike the Bloch-Siegert effect, the dynamical Zeeman effect depends on the detuning sign. Our theoretical results are in a good agreement with the experimental data obtained in pulse EPR for the $E'_{1}$ centers in crystalline quartz.