近日，德国马克斯·普朗克量子光学研究所的Shubhadeep Biswas及其研究小组与西班牙马德里材料科学研究所的Álvaro Jiménez-Galán等人合作并取得一项新进展。经过不懈努力，他们实现单层六方氮化硼中的光波控制霍尔丹模型。相关研究成果已于2024年4月15日在国际权威学术期刊《自然》上发表。

该研究团队展示了一种定制光波驱动的扭曲层堆叠模拟技术。他们将光波形的空间对称性调整至与六方氮化硼单层晶格相匹配，随后通过扭转波形实现了对时间反演对称性破缺的光学控制，进而在激光修饰的二维绝缘晶体中实现了拓扑霍尔丹模型。

此外，通过旋转光波形，研究人员能够有效调控霍尔丹型哈密顿量的参数，实现能带结构配置间的超快速切换，并对带隙的大小、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布居，产生可测量的谷霍尔电流，这可以通过光学谐波偏振法检测到。该方案的通用性和鲁棒性为动态谷选择性带隙工程铺平了道路，并预示着具有量子自由度的少飞秒开关的创建将成为可能。

据悉，近年来，研究人员通过堆叠和扭曲具有匹配晶体对称性的原子薄结构，成功开创了一种构建新型超晶格结构的独特方法，这种方法使得新性质在超晶格结构中得以显现。与此同时，对强光场时间特性的精准控制，使得研究人员能够在亚激光周期的时间尺度上，精细调控这种原子薄结构中的相干电子输运过程。

附：英文原文

Title: Light-wave-controlled Haldane model in monolayer hexagonal boron nitride

Author: Mitra, Sambit, Jimnez-Galan, Alvaro, Aulich, Mario, Neuhaus, Marcel, Silva, Rui E. F., Pervak, Volodymyr, Kling, Matthias F., Biswas, Shubhadeep

Issue&Volume: 2024-04-15

Abstract: 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. 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. 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 breaking and the realization of the topological Haldane model 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 current, 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.

DOI: 10.1038/s41586-024-07244-z

Source: https://www.nature.com/articles/s41586-024-07244-z