Under physiological conditions, ballistic long-range transfer of electronic excitations in molecular aggregates is generally expected to be suppressed by noise and dissipative processes. Hence, quantum phenomena are not considered to be relevant for the design of efficient and controllable energy transfer over significant length scales and timescales. Contrary to this conventional wisdom, here we show that the robust quantum properties of small configurations of repeating clusters of molecules can be used to tune energy-transfer mechanisms that take place on much larger scales. With the support of an exactly solvable model, we demonstrate that coherent exciton delocalization and dark states within unit cells can be used to harness dissipative phenomena of varying nature (thermalization, fluorescence, nonradiative decay, and weak intersite correlations) to support classical propagation over macroscopic distances. In particular, we argue that coherent delocalization of electronic excitations over just a few pigments can drastically alter the relevant dissipation pathways that influence the energy-transfer mechanism and thus serve as a molecular control tool for large-scale properties of molecular materials. Building on these principles, we use extensive numerical simulations to demonstrate that they can explain currently not-understood measurements of micron-scale exciton diffusion in nanofabricated arrays of bacterial photosynthetic complexes. Based on these results, we provide quantum design guidelines at the molecular scale to optimize both energy-transfer speed and range over macroscopic distances in artificial light-harvesting architectures.

中文翻译：

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室温下远距离能量传输的设计原则

在生理条件下，通常预期分子聚集体中电子激发的弹道长程转移会受到噪声和耗散过程的抑制。因此，量子现象被认为与在显着长度尺度和时间尺度上设计有效且可控的能量转移无关。与这种传统智慧相反，我们在这里展示了重复分子簇的小构型的强大量子特性可用于调整发生在更大规模上的能量转移机制。在完全可解模型的支持下，我们证明了晶胞内的相干激子离域和暗态可用于利用不同性质的耗散现象（热化、荧光、非辐射衰变、和弱点间相关性）以支持宏观距离上的经典传播。特别是，我们认为仅在少数颜料上电子激发的相干离域可以彻底改变影响能量转移机制的相关耗散途径，从而作为分子材料大规模特性的分子控制工具。基于这些原理，我们使用广泛的数值模拟来证明它们可以解释目前尚未理解的细菌光合复合物纳米制造阵列中微米级激子扩散的测量结果。基于这些结果，我们提供了分子尺度的量子设计指南，以优化人造光收集架构中宏观距离上的能量转移速度和范围。