Angle-resolved photoemission spectroscopy (ARPES), with its exceptional sensitivity to both the binding energy and the momentum of valence electrons in solids, provides unparalleled insight into the electronic structure of quantum materials. Over the past two decades, the advent of femtosecond lasers, which can deliver ultrashort and coherent light pulses, has ushered the ARPES technique into the time domain. Currently time-resolved ARPES (TR-ARPES) can probe ultrafast electron dynamics and the out-of-equilibrium electronic structure, providing a wealth of information that is otherwise unattainable in conventional ARPES experiments. This review begins with an introduction to the theoretical underpinnings of TR-ARPES followed by a description of recent advances in state-of-the-art ultrafast sources and optical excitation schemes. It then reviews paradigmatic phenomena investigated by TR-ARPES thus far, such as out-of-equilibrium electronic states and their spin dynamics, Floquet-Volkov states, photoinduced phase transitions, electron-phonon coupling, and surface photovoltage effects. Each section highlights TR-ARPES data from diverse classes of quantum materials, including semiconductors, charge-ordered systems, topological materials, excitonic insulators, Van der Waals materials, and unconventional superconductors. These examples demonstrate how TR-ARPES has played a critical role in unraveling the complex dynamical properties of quantum materials. The conclusion outlines possible future directions and opportunities.

中文翻译：

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量子材料的时间分辨 ARPES 研究

角分辨光电子能谱（ARPES）对固体中价电子的结合能和动量具有卓越的敏感性，为量子材料的电子结构提供了无与伦比的洞察力。在过去的二十年里，能够提供超短相干光脉冲的飞秒激光器的出现，将 ARPES 技术引入了时域。目前时间分辨 ARPES (TR-ARPES) 可以探测超快电子动力学和非平衡电子结构，提供传统 ARPES 实验无法获得的大量信息。本综述首先介绍 TR-ARPES 的理论基础，然后描述最先进的超快光源和光学激发方案的最新进展。然后回顾了迄今为止 TR-ARPES 研究的典型现象，例如非平衡电子态及其自旋动力学、Floquet-Volkov 态、光致相变、电子声子耦合和表面光电压效应。每个部分都重点介绍来自不同类别量子材料的 TR-ARPES 数据，包括半导体、电荷有序系统、拓扑材料、激子绝缘体、范德华材料和非常规超导体。这些例子展示了 TR-ARPES 如何在揭示量子材料复杂的动力学特性方面发挥着关键作用。结论概述了未来可能的方向和机会。