RUI: Spectroscopy of Many-Body Processes in Semiconductor Nanostructures

该奖项支持半导体量子点中电子动力学的理论和计算研究。主要的重点是了解多体相关和量子限制效应在光谱中的作用，可以使用时间分辨光谱技术观察。该项目的第一部分将讨论由高强度光脉冲激发的单量子点中强关联多激子态的结构。这些激发的能谱通过发射谱的精细结构出现。这种结构代表了一组窄线，对应于伴随光子发射的多体跃迁。特别感兴趣的是多体过程对光子时间相关统计的影响。该项目的第二部分涉及在磁场存在下环形量子点（纳米环）的超快非线性光学光谱。由于有限的纳米环尺寸，磁场通过调制激子结合能引起光吸收的Aharonov-Bohm效应。本文研究了库仑关联和Aharonov-Bohm效应在多激子相干动力学中的作用。该项目的第三部分涉及合作效应在自组装量子点系统发光中的作用。当从~ 102个量子点的系综收集发光光谱时，这些效应变得相关。在无序的存在下，辐射耦合发射器系统的本征态通过发射光谱的随机但重复的精细结构来表现它们自己。发射谱线的统计特性提供了量子点空间和能级分布的特征，强量子尺寸效应使得量子点结构中多体过程的理论描述变得复杂，需要非微扰的理论方法。该项目的完成将涉及各种分析和数值方法。研究结果将与现有的实验数据进行比较。本科生将积极参与该项目。该项目将在历史悠久的黑人大学环境中开展，并为代表性不足的群体的本科生提供更多的研究和教育机会。%该奖项支持非常快的光脉冲（低至几飞秒）与半导体量子点中的电子相互作用的理论和计算研究。这项工作有助于理解超快光谱技术及其用于探测电子之间的相关性，这些电子之间的相关性是由于它们相互作用而产生的。量子点独特的光学性质和可调谐性使它们成为许多技术应用的有吸引力的候选者，包括新型激光器，单光子光源以及量子计算机中的比特。本科生将积极参与该项目。该项目将在一个历史悠久的黑人大学环境中进行，并为代表性不足的群体的本科生提供更多的研究和教育机会。

This award supports theoretical and computational studies of electron dynamics in semiconductor quantum dots. The main focus is on understanding the role of many-body correlation and quantum confinement effects in optical spectra that can be observed using time-resolved optical spectroscopy techniques. The first part of the project will address the structure of the strongly correlated multiexciton states in single quantum dots excited by a high-intensity optical pulse. The energy spectrum of these excitations appears through the fine structure of the emission spectrum. This structure represents a set of narrow lines corresponding to the many-body transitions that accompany the emission of a photon. Of particular interest is the effect of many-body processes on the photon temporal correlation statistics. The second part of the project is related to ultrafast nonlinear optical spectroscopy of ring-shaped quantum dots (nanorings) in the presence of a magnetic field. Due to the finite nanoring size, the magnetic field gives rise to the Aharonov-Bohm effect on optical absorption by modulating the exciton binding energy. Here the role of Coulomb correlation and Aharonov-Bohm effects in the coherent dynamics of multiexciton states will be investigated. The third part of the project involves the role of cooperative effects in the luminescence from systems of self-assembled quantum dots. These effects become relevant when the luminescence spectra are collected from an ensemble of ~ 102 quantum dots. In the presence of disorder, the eigenstates of a system of radiatively coupled emitters manifest themselves through a random but repetitive fine structure of the emission spectrum. The statistics of the emission lines provide the fingerprints of the quantum dots spatial and level distributions.Theoretical description of many-body processes in these structures is complicated by strong quantum-size effects, which requires nonperturbative theoretical approaches. The completion of the project will involve a variety of analytical and numerical methods. The results will be compared to the available experimental data.Undergraduate students will actively participate in the project. The project will be carried out in a historically black university setting and enhances research and education opportunities for undergraduate students from underrepresented groups.%%%This award supports theoretical and computational investigations of very fast light pulses (down to several femtoseconds) interacting with electrons in semiconductor quantum dots. This work contributes to the understanding of ultrafast spectroscopy techniques and their use to probe the correlations among electrons that arise as a consequence of their interaction with each other. The unique optical properties and tunability of quantum dots make them attractive candidates for many technological applications including new types of lasers, single-photon light sources, and as bits in quantum computers. Undergraduate students will actively participate in the project. The project will be carried out in a historically black university setting and enhances research and education opportunities for undergraduate students from underrepresented groups.***