Effects of system-bath coupling on Photosynthetic heat engine: A polaron master equation approach

TL;DR

This study uses a polaron master equation to analyze how varying system-bath couplings influence charge transfer in a photosynthetic quantum heat engine, revealing the interplay of noise-assisted transport and localization effects.

Contribution

It introduces a polaron master equation approach to interpolate between weak and strong system-bath couplings in photosynthetic models, elucidating the mechanisms of charge transfer dynamics.

Findings

System-bath coupling affects charge transfer efficiency.

Temperature influences the balance between transport mechanisms.

Robustness of effective voltage against bath noise is observed.

Abstract

In this paper, we apply the polaron master equation, which offers the possibilities to interpolate between weak and strong system-bath coupling, to study how system-bath couplings affect charge transfer processes in Photosystem II reaction center (PSII RC) inspired quantum heat engine (QHE) model in a wide parameter range. The effects of bath correlation and temperature, together with the combined effects of these factors are also discussed in details. The results show a variety of dynamical behaviours. We interpret these results in terms of noise-assisted transport effect and dynamical localization which correspond to two mechanisms underpinning the transfer process in photosynthetic complexes: One is resonance energy transfer and the other is dynamical localization effect captured by the polaron master equation. The effects of system-bath coupling and bath correlation are incorporated in the effective system-bath coupling strength determining whether noise-assisted transport effect or dynamical localization dominates the dynamics and temperature modulates the balance of the two mechanisms. Furthermore, these two mechanisms can be attributed to one physical origin: bath-induced fluctuations. The two mechanisms is manifestations of dual role played by bath-induced fluctuations within respective parameter range. In addition, we find that the effec- tive voltage of QHE exhibits superior robustness with respect to the bath noise as long as the system-coupling strength is not too large.