论文标题
原始石墨烯中的光诱导的山谷
Light-Induced Valleytronics in Pristine Graphene
论文作者
论文摘要
二维六边形材料中的电子具有山谷的自由度，可用于编码和处理量子信息。山谷选择性激发受材料的带隙的圆形光共振，继续是valleytronics的基础。通常认为，由于系统的反式对称性，无法以全光值实现山谷选择性激发。在这里，我们证明，通过使用两个反向旋转的圆形极化场（基本和第二个谐波）组合，可以在原始石墨烯中实现山谷选择性激发和山谷选择性的高谐波产生。控制两种颜色之间的相对相，我们可以选择产生电子孔对和高阶谐波的山谷。我们还描述了一种用弱探针脉冲测量石墨烯中山谷极化的全光学方法。这项工作提供了一个强大的食谱，可以用零带隙和零浆果曲率的材料编写和读取谷选择性电子激发。
Electrons in two-dimensional hexagonal materials have valley degree of freedom, which can be used to encode and process quantum information. The valley-selective excitations, governed by the circularly polarised light resonant with the material's band-gap, continues to be the foundation of valleytronics. It is often assumed that achieving valley selective excitation in pristine graphene with all-optical means is not possible due to the inversion symmetry of the system. Here we demonstrate that both valley-selective excitation and valley-selective high-harmonic generation can be achieved in pristine graphene by using the combination of two counter-rotating circularly polarized fields, the fundamental and its second harmonic. Controlling the relative phase between the two colours allows us to select the valleys where the electron-hole pairs and higher-order harmonics are generated. We also describe an all-optical method for measuring valley polarization in graphene with a weak probe pulse. This work offers a robust recipe to write and read valley-selective electron excitations in materials with zero bandgap and zero Berry curvature.
