Quantum gases in moiré-ordered and reconstructed heterostructures: effective dimensionalities, hybrid states, and interactions

扭曲或晶格错配的二维过渡金属二硫族化合物的范德华异质结构为多粒子和相关电子物理的光学研究提供了丰富和通用的平台。这些类型的现象敏感地依赖于特定的材料结构，包括晶格和角度的不匹配，导致形成莫尔海姆-超晶格或局部和介观重构域。在为电子多粒子态的设计提供高度的灵活性和可调性的同时，它也要求对潜在的基本过程进行准确的描述。这激发了本项目的主要目标，即全面理解半导体范德华异质结构中的多体物理，这些多体物理控制着它们在线性和非线性体系中的光学响应。我们将讨论玻色子和费米子类型的准粒子的密度条件，如激子或电子-空穴等离子体及其混合物。具体来说，我们的目标是利用统一的材料平台，从低密度到高密度的所有相关量子限制制度，了解重构异质结构中有效的二维、一维和零维域的维度对光激发动力学和输运的影响。此外，我们将创建和控制混合，相互作用的moir<s:1>激子态，结合强激子-激子和激子-光子相互作用，实现可调谐的偶极极化电子学。最后，我们计划开发实验和理论方法，从外部操纵激子-激子相互作用的强度和符号，从排斥到吸引，以及跨越纯玻色和费米气体之间的边界，以触发不同的多体相的形成。为了实现这些目标，我们将结合最先进的样品制造技术和先进的实验方法，包括超空间和磁光谱，超快瞬态显微镜，结构表征，以及微观多体理论的电子和光学特性，直到高密度状态。最终，它将使我们能够解决在二维范德华异质结构的广泛领域中关键科学和技术进步的快速增长的研究领域的前沿的专题问题。

Van der Waals heterostructures of twisted or lattice-mismatched two-dimensional transition metal dichalcogenides emerged as rich and versatile platforms for optical studies of many-particle and correlated electron physics. These types of phenomena depend sensitively on the specific material configurations, including lattice and angular mismatch leading to the formation of moiré-superlattices or locally and mesoscopically reconstructed domains. While offering a high level of flexibility and tunability for the design of the electronic many-particle states, it also demands accurate descriptions of the underlying fundamental processes. This motivates the main goal of this project to develop comprehensive understanding of the many-body physics in semiconducting van der Waals heterostructures governing their optical response across linear and non-linear regimes. We will address a broad range of density conditions for both bosonic and fermionic types of quasiparticles, such as excitons or electron-hole plasma and their mixtures. Specifically, we aim to understand the impact of dimensionality from effectively two-, one-, and zero-dimensional domains in reconstructed heterostructures on the dynamics and transport of optical excitations, using a unified material platform for all relevant quantum confinement regimes from low to high densities. In addition, we will create and control hybrid, interacting moiré exciton states combining strong exciton-exciton and exciton-photon interactions towards tunable dipolar polaritonics. Finally, we plan to develop experimental and theoretical approaches to externally manipulate both the strength and sign of the exciton-exciton interactions from repulsive to attractive, as well as crossing the border between pure Bose and Fermi gases to trigger formation of distinct many-body phases on demand. To address these goals, we will combine state-of-the art sample fabrication techniques with advanced experimental methods including hyperspatial and magneto-spectroscopy, ultrafast transient microscopy, and structural characterization, as well as microscopic many-body theory of electronic and optical properties up to high density regimes. Ultimately it will allow us to address topical questions on the forefront of a rapidly growing research field towards key scientific and technological advances in the broad area of two-dimensional van der Waals heterostructures.