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 L-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.