Steady-State Analysis of Light-harvesting Energy Transfer Driven by Incoherent Light: From Dimers to Networks.
Steady-State Analysis of Light-harvesting Energy Transfer Driven by Incoherent Light: From Dimers to Networks.
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DOI：
10.1021/acs.jpclett.0c01648
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发表时间：
2020-07
期刊：
影响因子：
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通讯作者：
Pei-Yun Yang;Jianshu Cao
中科院分区：
文献类型：
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作者：
Pei-Yun Yang;Jianshu Cao
量子相干如何促进能量转移的问题一直是科学界争论的焦点。由于自然和人工捕光单元在静止条件下工作，我们通过非平衡稳态分析非相干太阳光照射下的一般分子二聚体来解决这个问题，然后将关键预测推广到任意复杂的激子网络。稳态分析的主要结果是相干-通量-效率关系：η = c ∑i <$jFij κj = 2c ∑i <$jJij Im [ρij]κ j其中c是归一化常数。在这个关系中，第一个等式表示能量传递效率$\eta$由捕获通量唯一地确定，捕获通量是通量F和用于在反应中心捕获的分支比$\kappa$的乘积，并且第二个等式表示能量传递通量F等效于由非对角密度矩阵的虚部测量的量子相干性，即，$ Fij = 2Jij Im [ρij]。相干通量效率的关系，严格和一般适用于任何激子网络的任意连接的稳态条件下，并不限于非相干辐射或非相干泵浦。对于非相干光下的光捕获系统，非平衡能量转移通量（即稳态相干性）由详细平衡的破坏和光激发的量子干涉驱动，并导致能量转移效率的优化。应该注意的是，稳态相干性或等效地能量转移通量是光诱导瞬态相干性、非均匀耗尽和系统浴相关性的组合结果，因此不一定与2D光谱中的量子拍频相关。这些发现通常适用于复杂的量子网络，并对量子光学和器件产生影响。
The question of how quantum coherence facilitates energy transfer has been intensively debated in the scientific community. Since natural and artificial light-harvesting units operate under the stationary condition, we address this question via a non-equilibrium steady-state analysis of a generic molecular dimer irradiated by incoherent sunlight and then generalize the key predictions to arbitrarily-complex exciton networks. The central result of the steady-state analysis is the coherence-flux-efficiency relation: η = c ∑i ≠ jFij κj = 2c ∑i ≠ jJij Im [ρij]κjwith c the normalization constant. In this relation, the first equality indicates that energy transfer efficiency $\eta$ is uniquely determined by the trapping flux, which is the product of flux F and branching ratio $\kappa$ for trapping at the reaction centers, and the second equality indicates that the energy transfer flux F is equivalent to quantum coherence measured by the imaginary part of the off-diagonal density matrix, i.e., $ Fij = 2Jij Im [ρij]. The coherence-flux-efficiency relation holds rigorously and generally for any exciton networks of arbitrary connectivity under the stationary condition and is not limited to incoherent radiation or incoherent pumping. For light-harvesting systems under incoherent light, non-equilibrium energy transfer flux (i.e. steady-state coherence) is driven by the breakdown of detailed balance and by the quantum interference of light-excitations and leads to the optimization of energy transfer efficiency. It should be noted that the steady-state coherence or, equivalently, the energy transfer flux is the combined result of light-induced transient coherence, inhomogeneous depletion, and system-bath correlation, and is thus not necessarily correlated with quantum beatings in 2D spectra. These findings are generally applicable to complex quantum networks and have implications for quantum optics and devices.