A high-temperature, high-pressure autoclave has been adapted for use with a high-field nuclear magnetic resonance spectrometer. The autoclave has an internal pressure range of atmospheric pressure to 1.5 kbar and a temperature range of 273 K to 1900 K. The autoclave is usable in a high field (8 T) magnet with a room temperature, 76.4 mm bore. The autoclave was tested using assorted nuclear species with resonant frequencies ranging from 57 to 70 MHz at pressures ranging from atmospheric pressure to 1220 bar and temperatures ranging from 273 K to 448 K. Previously, the autoclave was used in conjunction with an iron magnet at temperatures to 1900 K and pressures to 1.5 kbar. / Graduation date: 1997

Graduation date: 1995

No description available.

Building a quantum computer is a formidable challenge. In this thesis, we focus on two projects, which tackle very different aspects of quantum computation, and yet still share a common goal in hopefully getting us closer to implementing a quantum computer on a large scale. The first project involves a numerical error threshold calculation of a quantum error correcting code called a surface code. These are local check codes, which means that only nearest neighbour interaction is required to determine where errors occurred. This is an important advantage over other approaches, as in many physical systems, doing operations on arbitrarily spaced qubits is often very difficult. An error threshold is a measure of how well a given error correcting scheme performs. It gives the experimentalists an idea of which approaches to error correction hold greater promise. We simulate both toric and planar variations of a surface code, and numerically calculate a threshold value of approximately $6.0 \times 10^{-3}$, which is comparable to similar calculations done by others \cite{Raussendorf2006,Raussendorf2007,Wang2009}. The second project deals with coupling superconducting flux qubits together. It expands the scheme presented in \cite{Plourde2004} to a three qubit, two coupler scenario. We study L-shaped and line-shaped coupler geometries, and show how the coupling strength changes in terms of the dimensions of the couplers. We explore two cases, the first where the interaction energy between two nearest neighbour qubits is high, while the coupling to the third qubit is as negligible as possible, as well as a case where all the coupling energies are as small as possible. Although only an initial step, a similar scheme can in principle be extended further to implement a lattice required for computation on a surface code.

Building a quantum computer is a formidable challenge. In this thesis, we focus on two projects, which tackle very different aspects of quantum computation, and yet still share a common goal in hopefully getting us closer to implementing a quantum computer on a large scale. The first project involves a numerical error threshold calculation of a quantum error correcting code called a surface code. These are local check codes, which means that only nearest neighbour interaction is required to determine where errors occurred. This is an important advantage over other approaches, as in many physical systems, doing operations on arbitrarily spaced qubits is often very difficult. An error threshold is a measure of how well a given error correcting scheme performs. It gives the experimentalists an idea of which approaches to error correction hold greater promise. We simulate both toric and planar variations of a surface code, and numerically calculate a threshold value of approximately $6.0 \times 10^{-3}$, which is comparable to similar calculations done by others \cite{Raussendorf2006,Raussendorf2007,Wang2009}. The second project deals with coupling superconducting flux qubits together. It expands the scheme presented in \cite{Plourde2004} to a three qubit, two coupler scenario. We study L-shaped and line-shaped coupler geometries, and show how the coupling strength changes in terms of the dimensions of the couplers. We explore two cases, the first where the interaction energy between two nearest neighbour qubits is high, while the coupling to the third qubit is as negligible as possible, as well as a case where all the coupling energies are as small as possible. Although only an initial step, a similar scheme can in principle be extended further to implement a lattice required for computation on a surface code.

Josephson junctions are dissipationless elements used notably in superconducting nanocircuits. While being indispensable for the making of superconducting quantum bits, they are plagued by intrinsic noise mechanisms that reduce the coherence time of the quantum devices. An important source of such fluctuations may come from the non-cristallinity and disorder of the oxide layer sandwiched between the two superconducting leads. In this work, roughness in a Josephson junction is modeled as a set of pinholes with a universal bimodal distribution of transmission eigenvalues that sum incoherently in the noise power. Each of these channels is treated as a ballistic quantum point contact with a thin barrier that determines the transmission eigenvalue. The noise spectrum is calculated using the quasiclassical Green's function method to analyze high and low transmission limits at non-zero temperature for all interesting frequencies. As suggested by experiments, low transmission channels generate shot noise while fast switching between subgap states creates strong non-poissonian low-frequency noise. However, when analyzed for three different universal models of disorder, the principal contribution to noise is found to come from the partially opened channels. Finally, fluctuations of the noise from sample to sample is seen to be dominated by the contribution of opened channels which may reduce the reproducibility of results between different experiments.

Thesis (Ph. D.)--University of Texas at Austin, 2001. / Vita. Includes bibliographical references. Available also from UMI/Dissertation Abstracts International.

This is a scoping report that presents conclusions and recommendations regarding the potential relationship between the people of Monroe and Lenawee Counties, Michigan and proposal to consider locating the Superconducting Super Collider (SSC) in these counties. The study area is located within the two counties but includes only the extreme eastern portion of Lenawee County. This report discusses the social and cultural impacts that could derive from siting the SSC in these counties, the possible local resident responses to these potential SSC impacts, and potential statewide responses to the project. This scoping research was founded through a contract between the Michigan Energy and Resource Research Associations (MERRA) and the Institute for Social Research, The University of Michigan. Scoping g research was conducted between April 15, 1986 and August 31, 1986.

Not available / text

No description available.