Non-Markovian coherence dynamics of driven spin boson model: damped quantum beat or large amplitude coherence oscillation

TL;DR

This paper analytically investigates the driven spin boson model, revealing how weak and strong driving fields influence population difference and coherence, leading to damped or large-amplitude oscillations.

Contribution

It provides explicit analytical expressions for population difference and coherence, elucidating the transition from damped to undamped oscillations under varying driving strengths.

Findings

Weak driving causes damped coherent oscillations in population difference.

Strong driving results in undamped, large-amplitude coherence oscillations.

The model's behavior bridges dissipationless and non-driven limits.

Abstract

The dynamics of driven spin boson model is studied analytically by means of the perturbation approach based on a unitary transformation. We gave the analytical expression for the population difference and coherence of the two level system. The results show that in the weak driven case, the population difference present damped coherent oscillation (single or double frequency) and the frequencies depend on the initial state. The coherence exhibit damped oscillation with Rabi frequency. When driven field is strong enough, the population difference exhibit undamped large-amplitude coherent oscillation. The results easily return to the two extreme cases without dissipation or without periodic driven.