发表机构
Politecnico di Milano; Istituto di Fotonica e Nanotecnologie, Consiglio Nazionale delle Ricerche; The Hebrew University of Jerusalem（米兰理工大学; 国家研究委员会光子学与纳米技术研究所; 耶路撒冷希伯来大学）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
本文提出一种新框架，将超快非线性光谱信号与激发条件和多体相互作用直接关联，预测两类动态非线性，并在CdSe/CdS量子点上验证，实现无模型重建激子动力学。
AI 中文摘要
非线性光谱被广泛用于探测物质中的超快动力学。更高非线性阶的信号编码了有价值的多体动力学，但直到最近才可单独提取。然而，它们基于双面费曼图的物理解释既繁琐又不直观。在此，我们建立了一个替代框架，将这些信号与潜在的激发条件和多体相互作用联系起来。该方法预测了两类动态非线性，分别源于直接多体相互作用或可饱和的动力学通道。该方法为提取的信号提供了直接的物理解释，阐明了其符号、幅度和动力学。它还使得能够从给定数量的激子出发，对粒子子集进行无模型的重建动力学，我们证明这特别有洞察力。我们使用胶体CdSe/CdS核/壳量子点验证了该框架，这使我们能够分别以及组合地模拟两类非线性。
英文摘要
Nonlinear spectroscopy is widely used to probe ultrafast dynamics in matter. Signals of higher nonlinear orders encode valuable many-body dynamics but only recently have become individually retrievable. However, their physical interpretation in terms of double-sided Feynman diagrams is cumbersome and non-intuitive. Here, we establish an alternative framework that connects them to the underlying excitation conditions and many-body interactions. This approach predicts two classes of dynamic nonlinearities, due either to direct many-body interactions or to saturable kinetic channels. The method provides a direct physical interpretation of the retrieved signals, explaining their sign, magnitude, and dynamics. It also enables model-free reconstruction of the dynamics of a sub-ensemble of particles starting with a given number of excitons, which we demonstrate to be especially insightful. We validate the framework using colloidal CdSe/CdS core/shell quantum dots, which enable us to model nonlinearities of both classes in isolation and also combined.
Comments15 pages, 7 figures
