标题： 整数和分数量子霍尔绝缘体的光控 显示英文标题

标题： Optical Control of Integer and Fractional Chern Insulators

摘要： 光学控制拓扑结构，尤其是在电子关联存在的情况下，是一个具有广泛科学和技术影响的迷人课题。扭曲的MoTe$_2$双层（tMoTe$_2$）是一种新发现的零场分数陈绝缘体（FCI），表现出分数化量子异常霍尔（FQAH）效应。由于边缘态的手性和陈数的符号由底层铁磁极化决定，操控铁磁性将实现对CI/FCI态的控制。在这里，我们通过tMoTe$_2$中的圆偏振光泵浦实现了铁磁极化的控制和切换，从而实现了CI和FCI态的控制。在低光激发功率下，我们通过光学训练实现了按需制备铁磁极化，即通过电调制系统从非铁磁状态转变为期望的铁磁状态，并伴随螺旋选择性光泵浦。随着激发功率的增加，我们在远低于居里温度的温度下实现了铁磁极化直接的光开关。光学训练和铁磁性的直接开关在CI/FCI态附近最有效，我们认为这是由于光注入空穴的间隙增强谷极化所致。我们表明，通过调节光激发的螺旋性可以动态地切换磁化。空间分辨测量进一步证明了铁磁性的光学写入，从而实现了CI（或FCI）畴的光学写入。我们的工作实现了对拓扑量子多体系统的精确光学控制，具有在拓扑自旋电子学、量子存储器以及通过整数和分数QAH畴的可编程图案化创建奇异边缘态方面的潜在应用。 显示英文摘要

摘要： Optical control of topology, particularly in the presence of electron correlations, is a fascinating topic with broad scientific and technological impact. Twisted MoTe$_2$ bilayer (tMoTe$_2$) is a newly discovered zero-field fractional Chern insulator (FCI), exhibiting the fractionally quantized anomalous Hall (FQAH) effect. Since the chirality of the edge states and sign of the Chern number are determined by the underlying ferromagnetic polarization, manipulation of ferromagnetism would realize control of the CI/FCI states. Here, we demonstrate control and switching of ferromagnetic polarization, and thus the CI and FCI states by circularly polarized optical pumping in tMoTe$_2$. At low optical excitation power, we achieve on-demand preparation of ferromagnetic polarization by optical training, i.e., electrically tuning the system from non-ferromagnetic to desirable ferromagnetic states accompanied with helicity-selective optical pumping. With increased excitation power, we further realize direct optical switching of ferromagnetic polarization at a temperature far below the Curie temperature. Both optical training and direct switching of ferromagnetism are most effective near CI/FCI states, which we attribute to a gap enhanced valley polarization of photo-injected holes. We show that the magnetization can be dynamically switched by modulating the helicity of optical excitation. Spatially resolved measurements further demonstrate optical writing of a ferromagnetic, and thus a CI (or FCI) domain. Our work realizes precise optical control of a topological quantum many-body system with potential applications in topological spintronics, quantum memories, and creation of exotic edge states by programmable patterning of integer and fractional QAH domains.