Ultrafast, multi-dimensional spectroscopic measurements of photosynthetic light-harvesting complexes have revealed quantum coherences with timescales comparable to those of energy-transfer processes. These observations have led to a debate regarding the states that give rise to the coherences and whether the presence of the coherences has implications for photosynthetic light harvesting. In these experiments, laser pulses create a coherent superposition of quantum states with a defined phase relationship across an ensemble, which gives rise to the quantum coherence and associated quantum beating signal. Dephasing of these quantum coherences, seen as a decay of the beating signal, is among the most sensitive probes of the interactions between a system and its surrounding environment. In this Review, we discuss the proposed origin and assignment of the observed quantum coherences in photosynthetic systems as electronic, vibronic or vibrational. We describe the latest experimental efforts towards unravelling the nature of the coherences, in particular ultrafast, two-dimensional electronic spectroscopy, as well as the accompanying theoretical and computational results. We discuss how measuring coherences can inform us about the excited-state dynamics of biophysical and chemical systems relevant to natural light harvesting and how these measurements reveal electronic structure beyond that captured by simplistic models.

光合光捕获复合物的超快速多维光谱测量显示出量子相干性，其时间尺度可与能量转移过程相媲美。这些观察结果引发了关于引起相干性的状态以及相干性的存在是否对光合作用光收获有影响的辩论。在这些实验中，激光脉冲在整个集成体中以定义的相位关系创建了量子态的相干叠加，从而产生了量子相干性和相关的量子跳动信号。这些量子相干的相移被视为跳动信号的衰减，是对系统与其周围环境之间相互作用的最敏感的探查之一。在这篇评论中，我们讨论了光合系统中电子，振动或振动的拟议起源和观测到的量子相干的分配。我们描述了为弄清相干性而进行的最新实验工作，特别是超快速二维电子光谱学，以及随附的理论和计算结果。我们讨论测量相干性如何使我们了解与自然光收集有关的生物物理和化学系统的激发态动态，以及这些测量如何揭示超出简单模型所捕获的电子结构。二维电子光谱，以及随附的理论和计算结果。我们讨论测量相干性如何使我们了解与自然光收集有关的生物物理和化学系统的激发态动态，以及这些测量如何揭示超出简单模型所捕获的电子结构。二维电子光谱，以及随附的理论和计算结果。我们讨论测量相干性如何使我们了解与自然光收集有关的生物物理和化学系统的激发态动态，以及这些测量如何揭示超出简单模型所捕获的电子结构。