Dynamics of a two-level system under the simultaneous influence of a spin bath and a boson bath

TL;DR

This paper investigates the complex dynamics of a two-level quantum system interacting with both a spin bath and a boson bath, revealing how different couplings influence energy transfer, population transfer, and superposition state generation.

Contribution

It introduces a model of a two-level system coupled to dissimilar reservoirs with finite interbath coupling, analyzing steady-state and transient behaviors, and demonstrating robust superposition state generation.

Findings

Steady-state energy transfer increases with spin bath coupling.

Optimal transient energy transfer occurs at intermediate coupling.

Strong coupling to the spin bath leads to unidirectional population transfer.

Abstract

We study dynamics of a two-level system coupled simultaneously to a pair of dissimilar reservoirs, namely, a spin bath and a boson bath, which are connected via finite interbath coupling. It is found that the steady-state energy transfer in the two-level system increases with its coupling to the spin bath while optimal transfer occurs at intermediate coupling in the transient process. If the two-level system is strongly coupled to the spin bath, the population transfer is unidirectional barring minor population oscillations of minute amplitudes. If the spin bath is viewed as an atomic ensemble, robust generation of macroscopic superposition states exists against parameter variations of the two-level system and the boson bath.