Rerouting Excitation Transfer in the Fenna-Matthews-Olson Complex

TL;DR

This study uses the Hierarchy method to analyze how local modifications in the Fenna-Matthews-Olson complex affect entanglement and excitation transfer efficiency, revealing robustness and redundant pathways in energy transfer.

Contribution

It demonstrates that specific site disconnections can enhance transfer efficiency and entanglement, highlighting the complex's robustness and potential redundancy in energy pathways.

Findings

Disconnecting site-5 from the complex increases transfer efficiency.

Inhibiting the connection between site-5 and site-6 enhances entanglement.

Removing both site-5 and site-7 reduces transfer efficiency.

Abstract

We investigate, using the Hierarchy method, the entanglement and the excitation transfer efficiency of the Fenna-Matthews-Olson complex under two different local modifications: the suppression of transitions between particular sites and localized changes to the protein environment. We find that inhibiting the connection between the site-5 and site-6, or disconnecting site-5 from the complex completely, leads to an dramatic enhancement of the entanglement between site-6 and site-7. Similarly, the transfer efficiency actually increases if site-5 is disconnected from the complex entirely. We further show that if site-5 and site-7 are conjointly removed, the efficiency falls. This suggests that while not contributing to the transport efficiency in a normal complex, site-5 introduces a redundant transport route in case of damage to site-7. Our results suggest an overall robustness of excitation energy transfer in the FMO complex under mutations, local defects, and other abnormal situations.