Exciton-Phonon Information Flow in the Energy Transfer Process of Photosynthetic Complexes

Abstract

Non-Markovian and non-equilibrium phonon effects are believed to be key ingredients in the energy transfer in photosynthetic complexes, especially in complexes which exhibit a regime of intermediate exciton-phonon coupling. In this work, we harness a recently developed measure for non-Markovianity to elucidate the information flow between electronic and vibrational degrees of freedom. We study the measure in the hierarchical equation of motion approach which captures strong system-bath coupling effects and non-equilibrium molecular reorganization. We find that, for a model dimer system and the Fenna-Matthews-Olson complex, non-Markovianity is significant under realistic physiological conditions. A first step towards experimental quantification is provided by the study of four-wave mixing initial states.