Quantum Coherent Dynamics at Ambient Temperature in Photosynthetic Molecules

TL;DR

This paper investigates the surprisingly long-lived quantum coherence in photosynthetic molecules at room temperature, deriving a master equation to explain the phenomenon and its role in efficient energy transfer.

Contribution

It introduces a quantum master equation model that accounts for long coherence times in photosynthetic complexes at ambient conditions, aligning theoretical predictions with experimental data.

Findings

Quantum coherence persists for picoseconds at room temperature.

The model explains how coherence enhances energy transfer efficiency.

Calculated spectra and transfer rates match experimental observations.

Abstract

Photosynthetic antenna complexes are responsible for absorbing energy from sunlight and transmitting it to remote locations where it can be stored. Recent experiments have found that this process involves long-lived quantum coherence between pigment molecules, called chromophores, which make up these complexes. Expected to decay within 100 fs at room temperature, these coherences were instead found to persist for picosecond time scales, despite having no apparent isolation from the thermal environment of the cell. This paper derives a quantum master equation which describes the coherent evolution of a system in strong contact with a thermal environment. Conditions necessary for long coherence lifetimes are identified, and the role of coherence in efficient energy transport is illuminated. Static spectra and exciton transfer rates for the PE545 complex of the cryptophyte algae CS24 are calculated and shown to have good agreement with experiment.