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arXiv 1306.1319quant-ph
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FMO复合物相干激发转移的解析处理

Analytical Treatment of Coherent Excitation Transfer in FMO Complex

Pallavi Bhattacharyya, K. L. Sebastian

摘要:

我们提出了一种新的方法来研究耦合到环境中的有限能级系统的相干性,并将其用于描述捕光色素-蛋白质复合物的哈密顿量。该方法与绝热状态和转换的哈密顿量的形式,其中负责退相干和人口弛豫的条款被分离出来。退相干,然后占非微扰,人口松弛使用马尔可夫主方程。对于七能级系统,可以得到解析结果,对于多能级系统,计算非常简单。我们将这种处理方法应用于七能级系统,其结果与Nalbach等人的精确数值结果非常吻合。Braun和M. Thorwart,Physical Review E,84,041926(2011))。我们的方法是能够考虑退相干和人口松弛分开。发现退相干只引起振荡的衰减,并不导致向反应中心的转移。人口放宽是必要的有效转移到反应中心,与早期的研究结果一致。我们的研究结果表明,转换到绝热基础上的Redfield型的方法导致的结果与精确模拟吻合得很好。

英文摘要:

We suggest a new method of studying coherence in finite level systems coupled to the environment and use it for the Hamiltonian that has been used to describe the light-harvesting pigment-protein complex. The method works with the adiabatic states and transforms the Hamiltonian to a form in which the terms responsible for decoherence and population relaxation are separated out. Decoherence is then accounted for non-perturbatively, and population relaxation using a Markovian master equation. Analytical results can be obtained for the seven level system and the calculations are very simple for systems with more levels. We apply the treatment to the seven level system and the results are in excellent agreement with the exact numerical results of Nalbach et al. (P. Nalbach, D. Braun, and M. Thorwart, Physical Review E, 84, 041926 (2011)). Our approach is able to account for decoherence and population relaxation separately. It is found that decoherence only causes damping of oscillations, and does not lead to transfer to the reaction centre. Population relaxation is necessary for efficient transfer to the reaction centre, in agreement with earlier findings. Our results show that the transformation to the adiabatic basis followed by a Redfield type of approach leads to results in good agreement with exact simulation.

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