RUI: Spectroscopy of Many-Body Processes in Semiconductor Nanostructures

Jackson State University, Jackson MS

Investigators

Abstract

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. ***