固体高次谐波探测超快准粒子动力学

Quasiparticle dynamics is important for understanding many-body interactions in condensed matter physics. So far, its measurement still mostly relies on ultrafast pump-probe spectroscopy, which monitors the non-coherent relaxation dynamics. As a result, it precludes the possibility of further improving the time resolution to attosecond timescales, nor observing the microscopic dynamics throughout the generation and the annihilation of quasiparticles is possible. Fortunately, solid-state high harmonic generation (HHG) spectroscopy have provided us with a novel method to study these processes in microscopic details, utilizing the spatial and temporal coherence of the HHG process, as well as the high sensitivity of the emitted spectrum to the quantum trajectories of particles in a material. Until now, the fundamental mechanism of solid-state HHG is still under debate. Its application as a spectroscopic tool has also been limited to semiconductors and insulators. In this work, we propose that we can use a carrier-envelope-phase-stabilized strong-field terahertz source to drive HHG processes and coherently probe quasiparticle dynamics in various materials, including two-dimensional electron systems and high-temperature superconductors, etc. From the results, we will study the fundamental mechanism of solid-state HHG in more details, coherently probe the quasiparticle dynamics with attosecond-to-femtosecond time resolutions. We will also investigate many-body interactions using the quasiparticle quantum trajectories extracted from solid-state HHG spectroscopy, by comparing experimental results with theoretical simulations.

凝聚态材料中的准粒子激发以及湮灭过程一直以来是一个被广泛研究的课题，对于理解材料中的多体相互作用具有重要的意义。目前，对于准粒子动力学的探测仍然局限于对非相干的弛豫过程的测量，因此实验上无法进一步提高测量的时间精度，掌握准粒子从产生到湮灭的完整微观动力学过程。固体高次谐波利用了高次谐波产生过程的相干性以及产生光谱对粒子量子轨迹的依赖性，为我们提供了一种全新的相干探测材料中超快准粒子动力学的方法。至今固体高次谐波的产生机理仍有争议，而研究对象也仍然局限于常规半导体材料。在这项研究中，我们提出使用载波波洛相位稳定的强场太赫兹光源驱动固体高次谐波，相干探测包括二维电子材料、高温超导体等材料中的准粒子超快动力学。通过实验结果，我们将进一步研究固体高次谐波的产生机制，以飞秒至阿秒的时间精度重塑准粒子的量子轨迹，并与理论模拟相结合通过固体高次谐波光谱研究材料中的多体相互作用等重要物理问题。

凝聚态材料中的准粒子激发以及湮灭过程一直以来是一个被广泛研究的课题，对于理解材料中的多体相互作用具有重要的意义。目前，对于准粒子动力学的探测仍然局限于对非相干的弛豫过程的测量，且仅能研究弱场条件下的退相干弛豫过程。在本项目执行过程中，通过发展新型强场太赫兹光源、光场调控技术，以及高效率高质量的近红外光脉冲压缩技术，实现了对半导体材料激子态在强场下退相干过程的相干探测。通过实验和理论结果对比，揭示了强场缀饰下半导体激子加速退相干的重要物理机制。本项目的研究成果将为强场光物质调控研究发展重要的理论基础。同时，本项目也发展了重要的超快光学技术，包括基于孤子态的高效率光脉冲压缩，基于自旋电子-超构表面的太赫兹产生和光场调控技术，以及高亮度高次谐波光源技术等。这些技术将为更广泛的光激发凝聚态材料的物性探测提供重要的实验工具。