Long-Lived Electronic Coherence in Dissipative Exciton-Dynamics of Light-Harvesting Complexes

TL;DR

This paper reveals a generic mechanism enabling long-lived electronic coherence in light-harvesting complexes at room temperature, crucial for understanding efficient energy transfer in noisy biological environments.

Contribution

It identifies how specific spectral density properties support sustained electronic coherence, advancing knowledge of exciton dynamics in biological systems.

Findings

Coherence persists up to 0.3 ps at 277 K.

Large dissipative coupling to high-frequency vibrations is essential.

Small slope of spectral density at zero frequency promotes coherence.

Abstract

The observed prevalence of oscillatory signals in the spectroscopy of biological light-harvesting complexes at ambient temperatures has led to a search for mechanisms supporting coherent transport through larger molecules in noisy environments. We demonstrate a generic mechanism supporting long-lasting electronic coherence up to 0.3 ps at a temperature of 277 K. The mechanism relies on two properties of the spectral density: (i) a large dissipative coupling to a continuum of higher-frequency vibrations required for efficient transport and (ii) a small slope of the spectral density at zero frequency.