Dissertation/Thesis Abstract

Spin and Tunneling Effects in Coupled Quantum Dots
by Ramanathan, Swati, Ph.D., Ohio University, 2012, 136; 10631225
Abstract (Summary)

The study and control of individual carrier spins in semiconductor heterostructures can be effected by interaction with light. Owing to their high degree of tunability, the spectroscopic properties of vertically coupled InAs quantum dots grown on GaAs substrate are great candidates for study as they have not been fully characterized. The central theme of this dissertation is therefore to collect spectroscopic information, with the ultimate aim of identification and characterization of the spin and charge properties of quantum dots to help lay the groundwork for future uses in optical devices and design of efficient and reliable qubit states for quantum computers.

The main results of this work include : (i) a detailed large sample size study of the electron and hole positions via dipole Stark shifts in various barrier sizes, leading to a model explaining how these positions are affected by quantum mechanical tunneling. This model successfully predicts the Stark shifts of previously unidentified exciton states; and (ii) the measurement of circular polarization memory properties of the various excitonic charge states that make up this system, which, in addition to aiding in the identification of the charge states in quantum dot molecules, reveal information about methods of mitigating the effects of the anisotropic exchange interaction, which is a potential spin decoherence mechanism. Finally, this work discusses in detail (iii) the design of a polarimetry setup to measure with a high degree of precision the Stokes parameters of the coupled quantum dot system, which elucidate the complete polarization state of the various charge states, with the ultimate goal of using this information to select the states that are best suited for quantum computation applications.

Indexing (document details)
Advisor: Stinaff, Eric A.
Commitee: Kordesch, Martin, Richardson, Hugh, Stinaff, Eric A., Ulloa, Sergio
School: Ohio University
Department: Physics and Astronomy (Arts and Sciences)
School Location: United States -- Ohio
Source: DAI-B 78/11(E), Dissertation Abstracts International
Subjects: Physics, Condensed matter physics
Keywords: Exciton, Nanostructures, Quantum dots, Quantum optics, Spin, Stark shift
Publication Number: 10631225
ISBN: 978-0-355-01501-0
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