Elucidating quantum coherence effects and geometrical factors for efficientenergy transfer in photosynthesis has the potential to uncover nonclassical designprinciples for advanced organic materials. We study energy transfer in a linear light-harvestingmodel to reveal that dimerized geometries with strong electronic coherenceswithin donor and acceptor pairs exhibit significantly improved efficiency, which is inmarked contrast to predictions of the classical Forster theory. We reveal that energytuning due to coherent delocalization of photoexcitations is mainly responsible for theefficiency optimization. This coherence-assisted energy-tuning mechanism also explainsthe energetics and chlorophyll arrangements in the widely studied Fenna−Matthews−Olson complex. We argue that a clustered network with rapid energy relaxation amongdonors and resonant energy transfer from donor to acceptor states provides a basicformula for constructing efficient light-harvesting systems, and the general principles revealed here can be generalized to largersystems and benefit future innovation of efficient molecular light-harvesting materials.
Assistant Prof. Qing Ai，received his Ph.D. degree from Department of Physics, Tsinghua University. He did post-doctoral research in Institute of Theoretical Physics, CAS, and Department of Chemistry, National Taiwan University. He is mainly interested in quantum coherence effects in biology, quantum information and quantum optics.