Noise-assisted energy transfer in quantum networks and light-harvesting complexes

TL;DR

This paper elucidates how noise, specifically dephasing, enhances excitation energy transfer in quantum networks like the FMO complex, achieving over 90% efficiency by modifying transfer pathways, with implications for designing artificial light-harvesting systems.

Contribution

It introduces a detailed, physically intuitive mechanism for noise-assisted energy transfer in quantum networks, emphasizing the robustness and potential for noise-engineering in artificial systems.

Findings

Noise enables high-efficiency energy transfer (>90%) in FMO complex.

Noise alters transfer pathways, suppressing ineffective ones.

The mechanisms are robust but sensitive to exciton-phonon coupling details.

Abstract

We provide physically intuitive mechanisms for the effect of noise on excitation energy transfer (EET) in networks. Using these mechanisms of dephasing-assisted transport (DAT) in a hybrid basis of both excitons and sites, we develop a detailed picture of how noise enables energy transfer with efficiencies well above $90%$ across the Fenna-Matthew-Olson (FMO) complex, a type of light harvesting molecule. We demonstrate explicitly how noise alters the pathways of energy transfer across the complex, suppressing ineffective pathways and facilitating direct ones to the reaction centre. We explain that the fundamental mechanisms underpinning DAT are expected to be robust with respect to the considered noise model but show that the specific details of the exciton-phonon coupling, which remain largely unknown in these type of complexes, and in particular the impact of non-Markovian effects, results in variations of dynamical features that should be amenable to experimental verification within current or planned technology. A detailed understanding of DAT in natural compounds should open up a new paradigm of `noise-engineering' by which EET can be optimized in artificial light-harvesting structures.