Fassioli Francesca, Olaya-Castro Alexandra, Scholes Gregory D
†Lash Miller Chemical Laboratories, Institute for Optical Sciences and Centre for Quantum Information and Quantum Control, University of Toronto, 80 St. George St., Toronto, Ontario, M5S 3H6, Canada.
‡Department of Physics and Astronomy, University College London, Gower Street, London WC1E 6BT, United Kingdom.
J Phys Chem Lett. 2012 Nov 1;3(21):3136-42. doi: 10.1021/jz3010317. Epub 2012 Oct 15.
Recent two-dimensional electronic spectroscopy (2DES) experiments have reported evidence of coherent dynamics of electronic excitations in several light-harvesting antennae. However, 2DES uses ultrafast coherent laser pulses as an excitation source; therefore, there is a current debate on whether coherent excitation dynamics is present under natural sunlight - incoherent - illumination conditions. In this letter, we show that even if incoherent light excites an electronic state with no initial quantum superpositions among excitonic states, energy transfer can proceed quantum coherently if nonequilibrium dynamics of the phonon environment takes place. Such nonequilibrium behavior manifests itself in non-Markovian evolution of electronic excitations and is typical of many photosynthetic systems. We therefore argue that light-harvesting antennae have mechanisms that could support coherent evolution under incoherent illumination.
最近的二维电子光谱（2DES）实验报告了在几种光捕获天线中电子激发的相干动力学证据。然而，2DES使用超快相干激光脉冲作为激发源；因此，目前存在关于在自然阳光（非相干）照射条件下是否存在相干激发动力学的争论。在这封信中，我们表明，即使非相干光激发了一个在激子态之间没有初始量子叠加的电子态，如果声子环境发生非平衡动力学，能量转移也可以量子相干地进行。这种非平衡行为表现为电子激发的非马尔可夫演化，并且是许多光合系统的典型特征。因此，我们认为光捕获天线具有能够在非相干照射下支持相干演化的机制。
