In recent years, the stacking and twisting of atom-thin structures with matching crystal symmetry has provided a unique way to create new superlattice structures in which new properties emerge^1,2. In parallel, control over the temporal characteristics of strong light fields has allowed researchers to manipulate coherent electron transport in such atom-thin structures on sublaser-cycle timescales^3,4. Here we demonstrate a tailored light-wave-driven analogue to twisted layer stacking. Tailoring the spatial symmetry of the light waveform to that of the lattice of a hexagonal boron nitride monolayer and then twisting this waveform result in optical control of time-reversal symmetry breaking⁵ and the realization of the topological Haldane model⁶ in a laser-dressed two-dimensional insulating crystal. Further, the parameters of the effective Haldane-type Hamiltonian can be controlled by rotating the light waveform, thus enabling ultrafast switching between band structure configurations and allowing unprecedented control over the magnitude, location and curvature of the bandgap. This results in an asymmetric population between complementary quantum valleys that leads to a measurable valley Hall current⁷, which can be detected by optical harmonic polarimetry. The universality and robustness of our scheme paves the way to valley-selective bandgap engineering on the fly and unlocks the possibility of creating few-femtosecond switches with quantum degrees of freedom.

近年来，具有匹配晶体对称性的原子薄结构的堆叠和扭曲提供了一种独特的方法来创建新的超晶格结构，其中出现了新的特性^1,2。与此同时，对强光场时间特性的控制使研究人员能够在亚激光周期时间尺度上操纵这种原子薄结构中的相干电子传输^3,4。在这里，我们演示了一种定制的光波驱动模拟扭曲层堆叠。将光波形的空间对称性调整为六方氮化硼单层晶格的空间对称性，然后扭曲该波形，从而实现时间反转对称性破缺的光学控制⁵以及在激光修整的两个器件中实现拓扑 Haldane 模型⁶立体绝缘晶体。此外，有效霍尔丹型哈密顿量的参数可以通过旋转光波形来控制，从而实现能带结构配置之间的超快切换，并允许对带隙的大小、位置和曲率进行前所未有的控制。这导致互补量子谷之间的不对称群体，从而产生可测量的谷霍尔电流⁷，该电流可以通过光学谐波偏振测定法检测到。我们方案的普遍性和鲁棒性为动态谷选择性带隙工程铺平了道路，并释放了创建具有量子自由度的几飞秒开关的可能性。