Physical Review A
Twofold decoherence brought on by the phonon bath in a quantum-dot two-state system
Zhide Chen
Abstract
Because of the inherent coupling, the influence from the phonon bath on the coherent energy exchange between a quantum-dot (QD) two-state system (TSS) and a resonant optical mode is a twofold action. One action is the influence on the construction of the coherence, and the other is on the constructed coherence. The latter has been extensively studied by the master-equation approach, whereas the former has been ignored so far. In the present paper, the influence from the phonon bath on the construction of the coherence is studied by using the small-polaron theory. It is found that in the presence of phonon coupling, the construction of the coherence depends on the state evolution of the phonon bath during the energy exchange. The coherence construction probability is calculated and found to be a decreasing function of both temperature and coupling strength. The spectrum including the twofold decoherence effect is calculated and the obtained result can help one to understand some peculiar observations in the photoluminescence spectrum of a QD TSS system, including the additional cavity line in the strong-coupling regime and the additional coherent scattering in the case of the Mollow triplet.