标题： 激子-极子相互作用在单层 WS$_2$ 显示英文标题

标题： Exciton-polaron interactions in monolayer WS$_2$

摘要： 准粒子之间的相互作用具有根本重要性，并最终决定了量子物质的宏观特性。 一个著名的例子是超导现象，它源于由声子甚至材料中更奇特的涨落介导的电子-电子吸引力。 在这里，我们将移动的激子杂质引入二维电子气中，并研究由此产生的费米极化子准粒子之间的相互作用。 我们对单层WS$_2$进行多维相干光谱分析，由于底层三子精细结构和谷特异性光学选择规则，这为确定极化子-极化子相互作用的性质提供了理想的平台。 在低电子掺杂密度下，我们发现主要的相互作用是被同一费米海修饰的极化子态之间的相互作用。 在没有束缚极化子对（双极化子）的情况下，我们通过一个最小微观模型表明，这些相互作用源自相空间填充效应，其中激子争夺相同的电子。 此外，我们揭示了一种具有显著大结合能的双极化子束缚态，涉及不同谷中的激子协同地与同一电子结合。 我们的工作为探测和理解二维层状结构（如莫尔超晶格）中的强电子关联效应奠定了基础。 显示英文摘要

摘要： Interactions between quasiparticles are of fundamental importance and ultimately determine the macroscopic properties of quantum matter. A famous example is the phenomenon of superconductivity, which arises from attractive electron-electron interactions that are mediated by phonons or even other more exotic fluctuations in the material. Here we introduce mobile exciton impurities into a two-dimensional electron gas and investigate the interactions between the resulting Fermi polaron quasiparticles. We employ multi-dimensional coherent spectroscopy on monolayer WS$_2$, which provides an ideal platform for determining the nature of polaron-polaron interactions due to the underlying trion fine structure and the valley specific optical selection rules. At low electron doping densities, we find that the dominant interactions are between polaron states that are dressed by the same Fermi sea. In the absence of bound polaron pairs (bipolarons), we show using a minimal microscopic model that these interactions originate from a phase-space filling effect, where excitons compete for the same electrons. We furthermore reveal the existence of a bipolaron bound state with remarkably large binding energy, involving excitons in different valleys cooperatively bound to the same electron. Our work lays the foundation for probing and understanding strong electron correlation effects in two-dimensional layered structures such as moir\'e superlattices.