The Assistance of Molecular Vibrations on Coherent Energy Transfer in Photosynthesis from the View of Quantum Heat Engine

TL;DR

This paper models a light-harvesting complex as a quantum heat engine to explore how molecular vibrations enhance coherent energy transfer, achieving high quantum yield through exciton-vibration interactions.

Contribution

It demonstrates that exciton-vibration coupling significantly improves quantum transport and coherence in a photosynthetic model, revealing new insights into energy transfer mechanisms.

Findings

Quantum yield exceeds 90% with exciton-vibration coupling

Vibrations enhance quantum coherence and exciton delocalization

Thermal relaxation and dephasing can facilitate energy transfer

Abstract

Recently the quantum nature in the energy transport in solar cell and light-harvesting complexes have attracted much attention, as being triggered by the experimental observations. We model the light-harvesting complex (i.e., PEB50 dimer) as a quantum heat engine (QHE) and study the effect of the undamped intra-molecule vibrational modes on the coherent energy transfer process and quantum transport. We find that the exciton-vibration interaction has non-trivial contribution to the promotion of quantum yield as well as transport properties of the quantum heat engine at steady state, by enhancing the quantum coherence quantified by entanglement entropy. The perfect quantum yield over 90% has been obtained, with theexciton-vibration coupling. We attribute these improvements to the renormalization of the electronic couplings effectively induced by exciton-vibration interaction and the subsequent delocalization of excitons. Finally we demonstrate that the thermal relaxation and dephasing can help the excitation energy transfer in PEB50 dimer.