This thesis describes the first realization and initial measurements of a linear array of seven quantum dots. The device was fabricated on a high mobility GaAs/AlGaAs heterostructure. Electron beam lithography was used to pattern critical features of the device, and 70 nm resolution was achieved. A 3He probe was used to measure the device at 300 mK. The design of the device allowed individual c...

We investigate the electronic transport through a single-level quantum-dot which is capacitively coupled to a charge-qubit. By employing the method of nonequilibrium Green's functions, we calculate the electric current through quantum dot at finite bias voltages. The Green's functions and self-energies of the system are calculated perturbatively and self-consistently to the second order of inte...

We present a microscopic theory for both equilibrium and nonequilibrium transport properties of coupled double quantum dots (DQD). A general formula for current tunneling through the DQD is derived by the nonequilibrium Green’s function method. Using a Hartree-Fock approach, effects of multilevel coupling and nonequilibrium electron distributions in resonant tunneling are considered. We find th...

We report the fabrication and characterization of a gate-defined double quantum dot formed in a Si/SiGe nanomembrane. In the past, all gate-defined quantum dots in Si/SiGe heterostructures were formed on top of strain-graded virtual substrates. The strain grading process necessarily introduces misfit dislocations into a heterostructure, and these defects introduce lateral strain inhomogeneities...

Abstract We recreate Sandia National Laboratories’ double quantum dot charge stability diagram simulation using their rate equation approach and compare our simulation’s results to some touchstone situations as well as their results. We find qualitative agreement between charge stability diagrams and extend the code to construct the charge stability diagram for a triple dot structure. We note h...

A quantum-dot hybrid qubit formed from three electrons in a double quantum dot has the potential for great speed, due to the presence of level crossings where the qubit becomes chargelike. Here, we show how to exploit the level crossings to implement fast pulsed gating. We develop one- and two-qubit dc quantum gates that are simpler than the previously proposed ac gates. We obtain closed-form s...

We present an overview of experimental steps taken towards using the spin of a single electron trapped in a semiconductor quantum dot as a spin qubit [Loss and DiVincenzo, Phys. Rev. A 57, 120 (1998)]. Fabrication and characterization of a double quantum dot containing two coupled spins has been achieved, as well as initialization and single-shot read-out of the spin state. The relaxation time ...

Quasi–static transport measurements are employed to characterize a few electron quantum dot electrostatically defined in a GaAs/AlGaAs heterostructure. The gate geometry allows observations on one and the same electron droplet within a wide range of coupling strengths to the leads. The weak coupling regime is described by discrete quantum states. At strong interaction with the leads Kondo pheno...

Coupled quantum dots are an example of the ubiquitous quantum double potential well. In a typical transport experiment, each quantum dot is also coupled to a continuum of states. Our approach takes this into account by using a Green’s function formalism to solve the full system. The time-dependant solution is then explored in different limiting cases. In general, a combination of coherent and i...

We perform measurements on an AlGaAs/GaAs double-quantum-dot structure, where dots are separated by an opaque barrier and each dot conductance is measured independently and simultaneously. We measure the Coulomb blockade oscillations ~CBOs! for each dot when the structure is configured for one and two dots. When configured as a single-dot device, we sweep the backgate and observe different CBO ...