Configuration-picture-description of carrier scattering in semiconductor quantum dots

半导体量子点目前被用作活性材料，用于新型光电器件中的多种应用。这包括从传统的半导体激光器，放大器和调制器到单光子源和纠缠光子对，这是量子信息技术的关键组件。强大的应用潜力和众多的优势，建立了活性材料，导致高的实验和理论研究活动在这一领域。在实际应用中，散射过程起着核心作用：它们提供光学活性电子态的载流子，并决定光学跃迁的退相干。特定激发条件下的载流子散射效率为器件设置了固有限制，例如发射饱和度、调制速率和操作温度范围。退相干的强度直接决定了发射线的宽度、相干性、纠缠度和其他发射性质。以前描述半导体纳米结构中散射过程和载流子相关性的理论模型都是使用单粒子布居，或者是基于期望值的近似展开。然而，特别是在量子点中，三维载流子限制和相对较少的电子构型，更强调电子相关效应。这个项目的范围包括量子点中电荷载流子散射过程的基于构型的描述、其数值实现，以及理论和实验之间的直接合作，以评估结果并提供新的推动力。出发点是单粒子状态，导致，在库仑相互作用的组合，多激子配置。在相邻的连续态的载流子的散射过程，以及载流子和声子之间的相互作用，制定在这些配置。这项工作将汇集来自非平衡绿色函数量子动力学模型和基于相关性的量子光学效应描述的专业知识。

Semiconductor quantum dots are currently being used as active material for a multitude of applications in novel optoelectronic devices. This ranges from conventional semiconductor lasers, amplifiers, and modulators to sources of single photons and entangled photon pairs, which are key components for quantum information technologies. Strong application potential and numerous advantages over established active materials have led to high experimental and theoretical research activity in this field. For practical purposes, scattering processes play a central role: They provide carriers in the optically active electronic states and determine the decoherence of optical transitions. The efficiency of carrier scattering for particular excitation conditions sets intrinsic limitations for devices, such as saturation of the emission, modulation rates, and the operative temperature regime. The strength of decoherence directly determines the emission line widths, coherence properties, degrees of entanglement, and other emission properties.Previous theoretical models for the description of scattering processes and carrier correlations in semiconductor nanostructures have used single-particle populations, or they were based on the approximate expansion of a hierarchy of expectation values. Particularly in quantum dots, however, the three-dimensional carrier confinement, and the comparatively small number of electronic configurations, puts a much stronger emphasis on electronic correlation effects. This places currently used methods in a new light and questions their applicability under certain excitation conditions, as demonstrated in current publications.The scope of this project comprises a configuration-based description of charge carrier scattering processes in quantum dots, its numerical implementation, as well as a direct collaboration between theory and experiment to evaluate the results and provide new impulses. Starting point are the single-particle states that lead, in combination with the Coulomb interaction, to the multi-exciton configurations. Scattering processes with carriers in adjacent continuum states, as well as the interaction between carriers and phonons, are formulated in terms of these configurations. This undertaking will bring together expertise from non-equilibrium Green's function quantum-kinetic models and the correlation-based descriptions of quantum-optical effects.