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Full-Text Articles in Physics
Spin Pumping In Lateral Double Quantum Dot Systems, Sabine S. Pelton
Spin Pumping In Lateral Double Quantum Dot Systems, Sabine S. Pelton
Electronic Theses and Dissertations
Electron transport in single lateral quantum dot (QD) and parallel lateral double quantum dot (DQD) systems is modeled using semiclassical rate equations. The Zeeman effect, in conjunction with resonant tunneling, is used to select the spin of electrons involved in transport. We show adiabatic spin pumping by periodic variation of the systems' confining parameters, namely the quantum point contacts (QPCs) dictating the boundaries of the dots, and the gate voltage applied to each dot. The limitations of adiabatic spin pumping are subsequently examined by counting the average spin pumped per cycle when frequency and interdot capacitance are adjusted.
Computational Study Of The Near Field Spontaneous Creation Of Photonic States Coupled To Few Level Systems, Sergio Tafur
Computational Study Of The Near Field Spontaneous Creation Of Photonic States Coupled To Few Level Systems, Sergio Tafur
Electronic Theses and Dissertations
Models of the spontaneous emission and absorption of photons coupled to the electronic states of quantum dots, molecules, N-V (single nitrogen vacancy) centers in diamond, that can be modeled as artificial few level atoms, are important to the development of quantum computers and quantum networks. A quantum source modeled after an effective few level system is strongly dependent on the type and coupling strength the allowed transitions. These selection rules are subject to the Wigner-Eckert theorem which specifies the possible transitions during the spontaneous creation of a photonic state and its subsequent emission. The model presented in this dissertation describes …
Tunneling Conductance Characterization Of A Quantum Dot In The Fractional Quantum Hall Regime, Douglas E. Willard
Tunneling Conductance Characterization Of A Quantum Dot In The Fractional Quantum Hall Regime, Douglas E. Willard
Electronic Theses and Dissertations
This work represents a first-principles calculation of the electron tunneling current into quantum dots in the fractional quantum Hall effect regime. The system under consideration consists of an idealized Scanning Tunneling Microscope (STM) tip and a quantum dot with disk geometry and interacting electrons in a transverse magnetic field. Within the context of this model the tunneling current between the STM tip and the dot is examined for spin-polarized electrons at and around a filling factor of 1/3. The current expression is based on a second-quantized Hamiltonian in which electrons in the dot are interacting, confined, and restricted to the …
Electro-Optical And All-Optical Switching In Multimode Interference Waveguides Incorporating Semiconductor Nanostructures, Nathan Bickel
Electro-Optical And All-Optical Switching In Multimode Interference Waveguides Incorporating Semiconductor Nanostructures, Nathan Bickel
Electronic Theses and Dissertations
The application of epitaxially grown, III-V semiconductor-based nanostructures to the development of electro-optical and all-optical switches is investigated through the fabrication and testing of integrated photonic devices designed using multimode interference (MMI) waveguides. The properties and limitations of the materials are explored with respect to the operation of those devices through electrical carrier injection and optical pumping. MMI waveguide geometry was employed as it offered advantages such as a very compact device footprint, low polarization sensitivity, large bandwidth and relaxed fabrication tolerances when compared with conventional single-mode waveguide formats. The first portion of this dissertation focuses on the characterization of …
New Laser Technologies Analysis Of Quantum Dot And Lithographic Laser Diodes, Abdullah Demir
New Laser Technologies Analysis Of Quantum Dot And Lithographic Laser Diodes, Abdullah Demir
Electronic Theses and Dissertations
The first part of this dissertation presents a comprehensive study of quantum dot (QD) lasers threshold characteristics. The threshold temperature dependence of a QD laser diode is studied in different limits of p-doping, hole level spacing and inhomogeneous broadening. Theoretical analysis shows that the threshold current of a QD laser in the limit of uniform QDs is not temperature independent and actually more temperature sensitive than the quantum well laser. The results also explain the experimental trends of negative characteristic temperature observed in QD lasers and clarify how the carrier distribution mechanisms inside and among the QDs affect the threshold …
Modeling And Design Of A Photonic Crystal Chip Hosting A Quantum Network Made Of Single Spins In Quantum Dots That Interact Via Single Photons, Hubert P. Seigneur
Modeling And Design Of A Photonic Crystal Chip Hosting A Quantum Network Made Of Single Spins In Quantum Dots That Interact Via Single Photons, Hubert P. Seigneur
Electronic Theses and Dissertations
In this dissertation, the prospect of a quantum technology based on a photonic crystal chip hosting a quantum network made of quantum dot spins interacting via single photons is investigated. The mathematical procedure to deal with the Liouville-Von Neumann equation, which describes the time-evolution of the density matrix, was derived for an arbitrary system, giving general equations. Using this theoretical groundwork, a numerical model was then developed to study the spatiotemporal dynamics of entanglement between various qubits produced in a controlled way over the entire quantum network. As a result, an efficient quantum interface was engineered allowing for storage qubits …