拓扑量子态的超快动力学研究

Topological quantum states compose one of the important cutting-edge research areas of condensed matter physics. Currently there are two major experimental challenges: detecting the non-trivial topological quantum states (e.g. the topological surface states, the Fermi arcs) and observing novel effects emergent from topological properties (e.g. chiral magnetic effect). Focusing on the interaction between light and topological quantum materials, we apply ultrafast optical spectroscopy to Dirac and Weyl topological semimetals. We will systematically investigate the quasi-particle ultrafast dynamics, the generation and detection of coherent phonons, and the angle-resolved as well as multiple wavelength range ultrafast spectroscopy. We aim to solve the key fundamental problems such as evidencing non-trivial topological quantum states by ultrafast spectroscopy, observing quantum effects due to topological properties, and realizing laser-induced non-trivial topological states. Based on the current techniques and theoretical investigations, we further extend experimental means by combining low temperature, high magnetic field, and THz ultrafast spectroscopy together, paving new ways for investigating topological states using ultrafast nonlinear optical means. We look forward to fundamental breakthroughs in the field of “interaction between light and topological quantum states”.

拓扑量子态是当前凝聚态物理前沿领域的重要研究内容。目前研究的主要挑战有两个方面：实验探测非平庸拓扑量子态（例如拓扑表面态、费米弧等），以及起源于拓扑属性的新奇物理效应（例如手性磁效应等）。本项目从光与拓扑量子材料的相互作用的角度出发，利用超快光谱学实验手段，对Dirac型和Weyl型拓扑半金属体系进行系统的准粒子超快动力学、相干态声子的产生探测、角分辨多波段的超快光谱等研究，旨在解决若干关键科学问题：采用超快光谱学手段探测新奇拓扑量子态的存在，观测拓扑属性引起的量子效应，以及实现激光诱导的拓扑非平庸量子态及其调控。在已有实验技术和理论研究的基础之上，拓展低温-磁场-THz光谱综合测量实验手段，探寻超快非线性光学手段研究拓扑量子态的新途径，在光与拓扑量子态的相互作用领域取得突破和进展。