High harmonic generation (HHG) from gas-phase atoms (or molecules) has opened up a new frontier in ultrafast optics, where attosecond time resolution and angstrom spatial resolution are accessible. The fundamental physical pictures of HHG are always explained by the laser-induced recollision of particle-like electron motion, which lay the foundation of attosecond spectroscopy. In recent years, HHG has also been observed in solids. One can expect the extension of attosecond spectroscopy to the condensed matter if a description capable of resolving the ultrafast dynamics is provided. Thus, a large number of theoretical studies have been proposed to understand the underlying physics of solid HHG. Here, we revisit the recollision picture in solid HHG and show some challenges of current particle-perspective methods, and present the recently developed wave-perspective Huygens–Fresnel picture for understanding dynamical systems within the ambit of strong-field physics.

中文翻译：

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固体中的高次谐波产生：粒子和波的观点


气相原子（或分子）的高次谐波产生（HHG）开辟了超快光学的新领域，可以实现阿秒时间分辨率和埃空间分辨率。 HHG 的基本物理图像总是通过激光引起的类粒子电子运动的碰撞来解释，这奠定了阿秒光谱的基础。近年来，在固体中也观察到了 HHG。如果提供了能够解析超快动力学的描述，人们就可以期待阿秒光谱学扩展到凝聚态物质。因此，人们提出了大量的理论研究来理解固体 HHG 的基本物理原理。在这里，我们重新审视固体 HHG 中的重碰撞图，并展示当前粒子视角方法的一些挑战，并提出最近开发的波视角惠更斯-菲涅耳图，用于理解强场物理范围内的动力系统。