Coherent excitation transfer via the dark-state channel in a bionic system

Light absorption and energy transfer were studied in a bionic system with donors and an acceptor. In the optimal case of uniform couplings, this seemingly complicated system was reduced to a three-level Λ-type system. With this observation, we showed that the efficiency of energy transfer through a dark-state channel, which is free of the spontaneous decay of the donors, was dramatically improved. After the overall average transfer time was evaluated, it was revealed that the time required for transfer through this channel was not optimal. To find the optimal parameters for the present system, we defined a new quantity, output power, which characterizes the average mean output of the whole transfer process. We estimated the optimal parameters of the system to achieve the maximum output power. The splitting behaviour of the maximum power may be used to explain the phenomenon of photosynthetic systems primarily absorbing two colours of light. A molecular ring structure used for photosynthesis in plants could influence the design of future solar panel technologies. H. Dong and co-workers at the Chinese Academy of Sciences in Beijing have demonstrated a theoretical light-harvesting model that mimics photosynthesis in plants. A central acceptor surrounded by a ring of donor molecules transforms light into energy through the excitation of electrons. The researchers modelled donors coupled to photons of a particular energy and then examined the energy transfer process between the acceptor and donors of different molecular states. According to their results, the presence of a ‘dark state’ — which occurs when a molecule can no longer absorb or emit photons — significantly improves the overall efficiency of energy transfer in these artificial photosystems.