Environment-Assisted Quantum Photo-Protection in Interacting Multi-Exciton Transfer Complexes

TL;DR

This paper explores how environment-induced dephasing and exciton interactions can enhance quantum transport efficiency and provide photo-protection in multi-exciton systems, with potential relevance to photosynthesis.

Contribution

It reveals a novel role of dephasing in reducing exciton current, demonstrating environment-assisted photo-protection in multi-exciton transfer complexes.

Findings

Weak excitations can generate multiple excitons beyond single-exciton models

Dephasing and exciton interactions reduce current, enabling photo-protection

Potential link to natural photo-protection mechanisms in photosynthesis

Abstract

Transport of excitons through transfer networks is a unique example where the interplay between quantum coherence and environment-induced dephasing leads to non-trivial effects. One exciting example is the "environment-assisted quantum transport", (ENAQT), where, counter intuitively, the environment interrupts quantum transport in a way that enhances the transfer efficiency. Here we show that the interplay between dephasing and quantum coherence can lead to an additional function in exciton transport - photo-protection, that is the reduction of current upon increased excitation. We start by demonstrating that even under weak coupling conditions, weak excitations can lead to multiple-exciton generation, thus going beyond the common single-exciton approximation. We then consider the transport of two excitons, and show that a interplay between dephasing and exciton-exciton interactions leads to a reduction in current, i.e. to photo-protection. The effect may be related to actual photo-protection observed in photosynthetic systems.