Enhancement of coherent energy transfer by disorder and temperature in light harvesting processes

TL;DR

This study models excitonic energy transfer in photosynthesis, revealing that disorder and temperature can enhance energy transport efficiency, which is robust against noise and disorder.

Contribution

It demonstrates that static disorder and thermal excitations can improve energy transfer in light-harvesting systems, a novel insight into photosynthetic efficiency.

Findings

Energy transport is robust against static disorder and thermal noise.

Increasing disorder and temperature can enhance energy transfer efficiency.

The model aligns with high efficiency observed in natural photosynthesis.

Abstract

We investigate the influence of static disorder and thermal excitations on excitonic energy transport in the light-harvesting apparatus of photosynthetic systems by solving the Schr\"{o}dinger equation and taking into account the coherent hoppings of excitons, the rates of exciton creation and annihilation in antennas and reaction centers, and the coupling to thermally excited phonons. The antennas and reaction centers are modeled, respectively, as the sources and drains which provide the channels for creation and annihilation of excitons. Phonon modes below a maximum frequency are coupled to the excitons that are continuously created in the antennas and depleted in the reaction centers, and the phonon population in these modes obeys the Bose-Einstein distribution at a given temperature. It is found that the energy transport is not only robust against the static disorder and the thermal noise, but it can also be enhanced by increasing the randomness and temperature in most parameter regimes. Relevance of our work to the highly efficient energy transport in photosynthetic systems is discussed.