Coherence and its Role in Excitation Energy Transfer in Fenna-Mathews-Olson Complex

TL;DR

This study demonstrates that quantum coherence among bacteriochlorophyll-a sites in the Fenna-Mathews-Olson complex is crucial for efficient excitation energy transfer, with coherence persisting at steady state due to environmental interactions.

Contribution

It reveals the essential role of coherence in energy transfer within the complex and models the effects of environmental inhomogeneity and vibronic modes on coherence.

Findings

Coherence facilitates excitation redistribution among BChla sites.

System remains partially coherent at steady state.

Environmental effects influence coherence dynamics.

Abstract

We show that the coherence between different bacteriochlorophyll-a (BChla) sites in the Fenna-Mathews-Olson complex is an essential ingredient for excitation energy transfer between various sites. The coherence delocalizes the excitation energy, which results in the redistribution of excitation among all the BChla sites in the steady state. We further show that the system remains partially coherent at the steady state. In our numerical simulation of the non-Markovian density matrix equation, we consider both the inhomogeneity of the protein environment and the effect of active vibronic modes.