No description available.

Since the discovery of conductance quantization within a nanostnucture, investigations have sought out causes to conductance fluctuations beyond the established plateaus. The focus of this work is to show the fundamental effects upon conductance due to longitudinal potentials and double quantum boxes when confined by hardwall boundaries. A theoretical model based upon a tight-binding recursive tureen's function methodology was modified to incorporate potential barrier variations. A qualitative evaluation, as well as, explanation of the model's results and limitations is discussed. / Department of Physics and Astronomy

Thesis (Ph.D.)--Australian National University, 2001.

Thesis (M.S.)--University of Akron, Dept. of Electrical and Computer Engineering, 2009. / "August, 2009." Title from electronic thesis title page (viewed 10/7/2009) Advisor, Ernie Pan; Co-Advisor, Nathan Ida; Committee members, Malik Elbuluk, Igor Tsukerman; Department Chair, Alex De Abreu Garcia; Dean of the College, George K. Haritos; Dean of the Graduate School, George R. Newkome. Includes bibliographical references.

No description available.

The computing power in terms of speed and capacity of today's digital computers has improved tremendously in the last decade. This improvement came mainly due to a revolution in manufacturing technology by developing the ability to manufacture smaller devices and by integrating more devices on a single die. Further development of the current technology will be restricted by physical limits since it won't be possible to shrink devices beyond a certain size. Eventually, classical electrical circuits will encounter the barrier of quantum mechanics. The laws of quantum mechanics can be used for building computing systems that work on the principles of quantum mechanics. Thus quantum computing has drawn the interest of many top scientists in the world. Ion Trap technology is one of the most promising prospective technologies for building quantum computers. This technology allows the placement of qubits - ions in 1-, 2- and 3-dimensional regular structures. Development of efficient algorithms and methodologies for designing reversible quantum circuits is one of the most rapidly growing areas of research. All existing algorithms for synthesizing quantum circuits use multi-input Toffoli gates that have very high quantum cost in terms of electromagnetic pulses. They also do not use the opportunity of regular structures provided by the Ion Trap technology. In this thesis I present a completely new methodology for synthesizing quantum circuits that use only small (3x3) Toffoli gates and new gate families that have similar properties and use regular structures. These methods are for both binary and multiple valued quantum circuits. All my methods require adding some limited number of ancilla qudits [sic] but dramatically decrease the quantum cost of the synthesized circuits. I also present a new family of gates called "D-gates" that allows synthesis of quantum and reversible logic functions using structures called layered diagrams. The designed circuits can be directly mapped to a Quantum Logic Array implemented using the Ion Trap technology.

This dissertation is devoted to efficient automated logic synthesis of reversible circuits using various gate types and initial specifications. These Reversible circuits are of interest to several modern technologies, including Nanotechnology, Quantum computing, Quantum Dot Cellular Automata, Optical computing and low power adiabatic CMOS, but so far the most important practical application of reversible circuits is in quantum computing. Logic synthesis methodologies for reversible circuits are very different than those for classical CMOS or other technologies. The focus of this dissertation is on synthesis of reversible (permutative) binary circuits. It is not related to general unitary circuits that are used in quantum computing and which exhibit quantum mechanical phenomena such as superposition and entanglement. The interest in this dissertation is only in logic synthesis aspects and not in physical (technological) design aspects of reversible circuits. Permutative quantum circuits are important because they include the class of oracles and blocks that are parts of oracles, such as comparators or arithmetic blocks, counters of ones, etc. Every practical quantum algorithm, such as the Grover Algorithm, has many permutative circuits. These circuits are also used in Shor Algorithm (integer factorization), simulation of quantum systems, communication and many other quantum algorithms. Designing permutative circuits is therefore the major engineering task that must be solved to practically realize a quantum algorithm. The dissertation presents the theory that leads to MP (Multi-Path) algorithm, which is currently the top minimizer of reversible circuits with no ancilla bits. Comparison of MP with other 2 leading software tools is done. This software allows to minimize functions of more variables and with smaller quantum cost that other CAD tools. Other software developed in this dissertation allows to synthesize reversible circuits for functions with "don't cares" in their initial specifications. Theory to realize functions from relational representations is also given. Our yet other software tool allows to synthesize reversible circuits for new types of reversible logic, for which no algorithm was ever created, using the so-called "pseudo-reversible" gates called Y-switches.

This dissertation describes the study of various nonlinear optical effects in both bulk and quantum-confined semiconductors. Transverse effects in increasing absorption optical bistability are considered in bulk CdS for both single beam and wave mixing geometries. Measurement of the temporal response of BiI₃ quantum dots is described using degenerate four-wave mixing and explained theoretically. Finally, the experimental techniques developed to measure the one- and two-photon absorption coefficients of CdS quantum dots in glass are described along with the latest theoretical description and interpretation of the experimental spectra. The basic theory of increasing absorption optical bistability is presented along with experimental observation of this effect in CdS at low temperature. Transverse effects in increasing absorption optical bistability were observed in single beam experiments with CdS at low temperatures. The ring structures observed experimentally are explained theoretically. Degenerate four-wave mixing performed with this nonlinearity is theoretically shown to produce new scattering orders compared with a standard Kerr analysis. Experimental observation of these new scattering orders is presented. The temporal response of the nonlinearity in a solution of BiI₃ quantum dots in acetonitrile is determined using degenerate four-wave mixing. The independent contributions to the phase-conjugate signal are determined for both of the spatial gratings induced in the solution. The observed temporal responses indicated that a thermal mechanism was responsible for the nonlinearity. A theoretical analysis based on a thermal nonlinearity is presented which provides good agreement with the observed responses. The experimental techniques necessary to measure the one- and two-photon absorption coefficients of CdS quantum dots are described. The resultant measurements of quantum dot samples with microcrystallites ranging from 3.6 to 10.8 nm in diameter indicate no splitting of the energy levels associated with the hole. Theoretical spectra indicate this can be partially explained by the inclusion of Coulombic effects of the charged electron-hole pair.

QC 351 A7 no. 66 / This volume is intended to be used as a text for two courses at the Optical Sciences Center. A major part of the volume consists of lecture notes on the theory of laser operation, written by M. O. Scully and M. Sargent III. These notes, developed under NSF sponsorship for a new quantum optics curriculum at the University of Arizona, were the basis of a new course "Quantum Optics," which was first offered during the 1969-70 academic year. After considerable editing they were again used during "The Physics of Quantum Electronics" summer course in Prescott, June 22 - July 3, 1970. The remainder of the volume consists of unpublished work presented at Prescott, most of which will be utilized in a new course on nonlinear optics. References are given to material presented that has already appeared in print.

This research was mainly focused on the design and optimization of aperture-based structures to achieve the greatest third harmonic conversion efficiency. It was discovered that by tuning the localized surface plasmon resonance to the fundamental beam wavelength, and by tuning the propagating surface plasmons resonance to the Bragg resonance of the aperture arrays, both the directivity and conversion efficiency of the third harmonic signal were enhanced. The influence of the gap plasmon resonance on the third harmonic conversion efficiency of the aperture arrays was also investigated. The resulted third harmonic generation (THG) from an array of annular ring apertures as a closed loop structure were compared to arrays of H-shaped, double nanohole and rectangular apertures as open-loop structures. The H-shaped structure had the greatest conversion efficiency at approximately 0.5 %. Moreover, it was discovered that the maximum THG did not result from the smallest gap; instead, the gap sizes where the scattering and absorption cross sections were equal, led to the greatest THG. The finite difference time domain (FDTD) simulations based on the nonlinear scattering theory were also performed. The simulation results were in good agreement with the experimental data. Moreover, a modified quantum-corrected model was developed to study the electron tunneling effect as a limiting factor of the THG from plasmonic structures in the sub-nanometer regime. / Graduate / 0544 / 0794 / 0752 / 0756 / mrnezami@gmail.com