The Research On Excited Energy Transfer And Coherence Of Photosynthetic Reaction Center

Photosynthesis is a fundamental biological process through which biomass is produced.In the initial step of the photosynthesis,light-harvesting pigment proteins capture photons,and then the energy is transferred to the photosynthetic reaction center,where charge separation occurs,and photon energy is converted into chemical energy.The efficiency of excited energy transfer is so high to arouse the interest of researchers.In this paper,we use quantum mechanics language to describe the excited energy transfer and investigate coherence of a single photon.Firstly,we thought that the reaction center of photosynthesis system could be described by using the quantum heat engine.The heat,work and heat-work conversion rate for models of photosynthetic reaction center as quantum heat engines consisting of two subsystems were investigated.It was shown that the first law of thermodynamics was held perfectly in the quantum thermal machines(quantum heat engine and refrigerator).The difference of two adjacent energy levels between two subsystems affected the efficiency of heat-work conversion.However,the degrees of coherence and entanglement of the system's initial state didn't have any significant influences on the heat-work conversion in the quantum thermal machines.Then,we proposed a scheme to identify photons with different coherent superposition states and investigate the influence of coherence on the process of energy transfer through studying 2D,third-order,non-linear rephasing spectra obtained from a kind of special photon echo experiment.The procedures of the experiment could be arranged as follows.First,we inputted photons(laser)into a fiber.Then,after they passed through the fiber,we took the output laser from the fiber as the light source to implement the photon echo experiment.Finally,the 2D,third-order,non-linear rephasing spectra could be obtained from the photon echo signals.According to the pattern of the 2D,third-order,non-linear rephasing spectra,we could determine how the coherence influences the process of energy transfer.