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Full-Text Articles in Condensed Matter Physics
Ultracold Rubidium And Potassium System For Atom Chip-Based Microwave And Rf Potentials, Austin R. Ziltz
Ultracold Rubidium And Potassium System For Atom Chip-Based Microwave And Rf Potentials, Austin R. Ziltz
Dissertations, Theses, and Masters Projects
In this dissertation we study the development of microwave and RF near-field potentials for use with atom chip trapped atomic gases. These potentials are inherently spin-dependent, able to target individual spin states simultaneously. In contrast with traditional atom chip potentials, these RF traps can be operated at arbitrary bias magnetic field strengths and thus be combined with magnetic Feshbach resonances. Furthermore, these potentials can strongly suppress the potential roughness that plagues traditional atom chip potentials. We present a dual chamber atom chip apparatus for generating ultracold 87Rb and 39K atomic gases. The apparatus produces quasi-pure Bose-Einstein condensates of 104 87Rb …
Quantum Monte Carlo Method For Boson Ground States: Application To Trapped Bosons With Attractive And Repulsive Interactions, Wirawan Purwanto
Quantum Monte Carlo Method For Boson Ground States: Application To Trapped Bosons With Attractive And Repulsive Interactions, Wirawan Purwanto
Dissertations, Theses, and Masters Projects
We formulate a quantum Monte Carlo (QMC) method for calculating the ground state of many-boson systems. The method is based on a field-theoretical approach, and is closely related to existing fermion auxiliary-field QMC methods which are applied in several fields of physics. The ground-state projection is implemented as a branching random walk in the space of permanents consisting of identical single-particle orbitals. Any single-particle basis can be used, and the method is in principle exact. We apply this method to an atomic Bose gas, where the atoms interact via an attractive or repulsive contact two-body potential parametrized by the s-wave …
A Study Of Molecular Order And Motion In Nematic Liquid Crystal Mixtures, Jon Michael Goetz
A Study Of Molecular Order And Motion In Nematic Liquid Crystal Mixtures, Jon Michael Goetz
Dissertations, Theses, and Masters Projects
Materials which flow like fluids, but possess anisotropic properties like molecular crystals, are called 'liquid crystals'. Studies of liquid crystals contribute to our understanding of how molecular orientation influences macroscopic properties. This thesis presents experimental and theoretical investigations of molecular order and dynamics in nematic liquid crystal systems. First, deuterium nuclear magnetic resonance is used to determine the degree of orientational order of both components of a liquid crystal mixture simultaneously. The temperature dependence of the four order parameters is interpreted using a newly developed mean field theory of nematic binary mixtures composed of biaxial molecules. Next, mean field theory …
A Superconducting Compact Hydrogen Maser Resonator, David B. Opie
A Superconducting Compact Hydrogen Maser Resonator, David B. Opie
Dissertations, Theses, and Masters Projects
The discovery of high critical temperature superconductors (HTSC) has raised the temperature at which the greatly reduced surface resistance, characteristic of superconducting materials, may be exploited. For microwave frequencies below 100 GHz, the surface resistance, R{dollar}\sb{lcub}s{rcub}{dollar}, at liquid nitrogen temperatures (77K) of the new HTSC materials is found to be better than copper measured at the same temperature and frequency. Consequently, the miniaturization of passive microwave components will be among the first applications of these new materials. This dissertation details the development, testing and evaluation of a superconducting compact hydrogen maser resonator made from electrophoretic Y{dollar}\sb1Ba\sb2Cu\sb3{dollar}O{dollar}\sb{lcub}7-\delta{rcub}{dollar} (YBCO). Such a resonator …