Energy transfer in photosynthesis mediated by resonant confinement of exciton-polariton

Abstract

The ultra efficiency of energy transfer in photosynthesis has important biological significance. The underlying mechanism of energy transfer has never stopped being explored. Possible roles of quantum mechanics behind the natural phenomenon lead to many explorations in the field. Yet conventional mechanisms based on Förster resonance energy transfer or localized quantum coherence effects face certain challenges in explaining the unusual efficiency. We hereby bring up the attention of the dual properties of wave and particle of quantum mechanics into this context. In a previous research, we attributed the success of a similar efficiency in an artificial photosynthesis experiment to a mechanism mediated by resonant confinement of exciton-polariton. This paper extends the work to biological photosynthesis in higher plants and green sulfur bacteria. We explore specifically whether the exciton-polaritons of light-harvesting pigments, constrained by the optical cavity resonance, can act as intermediate states to mediate energy transfer. Namely, the pigments give a full play to their dual roles, receiving sunlight in the form of particle-like excitons, and rapidly transferring them to the reaction centers in the form of wave-like polaritons for maximal energy utilization. Taking realistic structure and data into account and based on approximate theoretical models, our quantitative estimate shows that such a mechanism is indeed capable of explaining at least partly the efficiency of photosynthesis. With comprehensive discussion, many deficits in the theoretical modeling can be reasonably reduced. Thus the conclusion may be further strengthened by realistic situations. Meanwhile, the underlying approach may also be extended to e.g. photovoltaic applications and neural signal transmissions, offering similar mechanisms for other energy transfer processes.