Phonon-mediated excitation energy transfer in a detuned multi-sites system

Based on a ring-shaped arrangement of interacting two-level systems, we show the important role of the phonon-mediated quantum interference in excitation energy transfer, mimicking light-harvesting antenna in natural photosynthetic systems. The pigments in a ring-shaped photosynthetic system interact with the high-energy intramolecular vibrational mode, which arises from the vibrational motion of the scaffold of the system, with different coupling phases according to the position of each pigment respect to the vibrational motion. By investigating the model systems, we demonstrate that in the presence of large detuning between donor pigments and acceptor pigments, the efficiency of excitation transfer depends directly on the relative coupling phase between two adjacent pigments. Our model system, containing more pigments, shows a better robustness of the phonon-mediated excitation energy transfer. The present results are not only helpful in understanding natural photosynthesis, but also offer an optimal design principle for artificial photosynthesis.