Emergent electronic structure and optical properties in two-dimensional materials

作为二维材料家族的新成员，过渡金属二卤化物(TMDC)在单层极限下开始出现许多新的有趣的物理性质，如Brillion区边缘的直接带隙，非常强烈的光-物质相互作用，接近山谷自由度，以及屏蔽度降低的异常强的库仑相互作用等。在过去，我们已经在TMDC单层中发现了一个即使在室温下也是稳定的紧密束缚激子，并成功地利用超快光控制了它的谷相干性。这些非同寻常的性质，再加上该材料的柔性性质，引发了人们对柔性屏幕和触摸板等器件应用的极大兴趣。*在这个拟议的计划中，我们的主要重点是探索更多的新兴现象，如二维TMDDC中的拓扑莫尔图案、单光子发射体和稳定的Floquit态以及面向量子信息应用的相关异质结构。我们特别感兴趣的是利用新的实验技术，如光感应力显微镜、脉冲宽度可调的超快激光和高Q光学微腔来研究具有亚衍射空间分辨率的强光场中的TMDCs。在接下来的五年里，我们将研究TMDC量子点背后的形成机制，莫尔图案对TMDC异质结构光学性质的影响，以及Floquit态的热化过程等一系列有待解决的问题。此外，我们还将展示一些新的控制可能性，包括全谷伪自旋操纵，可调的拓扑绝缘体纳米结构阵列，以及光诱导的拓扑非平凡稳定的Floquit态。一种新型的表面等离子体辅助光学近场探测器也在我们的发展计划中。*拟议的研究将在物理、材料科学工程和电气工程方面产生重大影响。一方面，我们的研究将提供对固体中的拓扑效应和非平衡物理的基本理解。对TMDC的深入了解将有助于进一步提高基于2D材料/异质结构的器件的性能。另一方面，所提出的浮现现象有望与自旋和山谷自由度相结合，在一个集成的平台上实现可扩展的量子信息处理。

As a new member of the two dimensional material family, the transition metal dichalcogenide (TMDC) has attracted a lot of interest because many new fascinating physical properties start to emerge at the monolayer limit, such as a direct band gap at the edge of Brillion zone, extraordinarily intense light-matter interaction, access to the valley degree of freedom, and unusually strong Coulomb interaction with reduced screening. In the past, we have discovered a tightly bound exciton stable even at room temperature in TMDC monolayer and successfully controlled its valley coherence using ultrafast light. These extraordinary properties, together with the flexible nature of the material, have triggered tremendous interest in device applications such as flexible screens and touchpads.***In this proposed program, our main focus is to explore more emergent phenomena such as the topological Moiré pattern, single photon emitter, and steady Floquet state in 2D TMDCs and related heterostructures towards quantum information applications. We are particularly interested in employing new experimental techniques such as photoinduced force microscopy, ultrafast laser with tunable pulse duration, and high-Q optical micro cavity to study TMDCs in the intense optical field with sub-diffractional spatial resolution. Within the next five years, we will investigate a series of open questions such as the formation mechanism behind the TMDC quantum dot, the impact of Moiré pattern on the optical property of TMDC heterostructures, and the thermalization process of Floquet states. Moreover, we will demonstrate some new control possibilities including the full valley pseudospin manipulation, tunable topological insulator nanostructure array, and the optical induced topologically nontrivial steady Floquet state. A new type of surface-plasmon assisted optical nearfield probe is also in our development plan.***The proposed research will have a large impact in physics, material science engineering, and electrical engineering. On the one hand, our study will provide fundamental understanding of topological effects and nonequilibrium physics in solids. The deep insights obtained for TMDCs will help further improve the performance of 2D material/heterostructure based devices. On the other hand, the proposed emergent phenomena are promising to be combined with the spin and valley degrees of freedom to enable scalable quantum information processing in an integrated platform.