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

Thesis (Ph. D.)--University of Texas at Austin, 2006. / Vita. Includes bibliographical references.

Thesis (Ph. D.)--University of Washington, 2001. / Vita. Includes bibliographical references (leaves 75-83).

No description available.

The main work of this thesis involves the calculation, using the Bethe ansatz, of two of the signature quantities of the one-dimensional delta-function Bose gas. These are the density matrix and concomitantly its Fourier transform the occupation numbers, and the correlation function and concomitantly its Fourier transform the structure factor. The coefficient of the delta-function is called the coupling constant; these quantities are calculated in the finite-coupling regime, both expansions around zero coupling and infinite coupling are considered. Further to this, the density matrix in the infinite coupling limit, and its first order correction, is recast into Toeplitz determinant form. From this the occupation numbers are calculated up to 36 particles for the ground state and up to 26 particles for the first and second excited states. This data is used to fit the coefficients of an ansatz for the occupation numbers. The correlation function in the infinite coupling limit, and its first order correction, is recast into a form which is easy to calculate for any N, and is determined explicitly in the thermodynamic limit.

Dissertation (Ph.D.)--University of Toledo, 2007. / Typescript. "Submitted as partial fulfillment of the requirements for The Doctor of Philosophy Degree in Physics." Bibliography: leaves 87-90.

Thesis (Ph. D.)--Physics, Georgia Institute of Technology, 2006. / Z. John Zhang, Committee Member ; Mei-Yin Chou, Committee Member ; Chandra Raman, Committee Member ; Michael S. Chapman, Committee Member ; Li You, Committee Chair. Vita. Includes bibliographical references.

Tese (doutorado) - Universidade Federal de Santa Catarina, Centro de Ciências Físicas e Matemáticas. Programa de Pós-Graduação em Física. / Made available in DSpace on 2012-10-21T20:46:57Z (GMT). No. of bitstreams: 0Bitstream added on 2013-07-16T19:40:32Z : No. of bitstreams: 1 205193.pdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Aplicação de um método analítico não perturbativo, conhecido como a expansão d linear desenvolvido para resolver problemas em teoria quântica de campos, para tratar dois problemas pertencentes à física da matéria condensada. É feita a estensão do cálculo do desvio da temperatura crítica de um gás de Bose homogêneo, diluído e fracamente interagente até a ordem d4, e também, é mostrado como o método deve ser implementado para se calcularem os expoentes críticos h e n em teorias escalares (f4) tridimensionais. A prescrição é ilustrada através de um cálculo explícito até a ordem d2.

In this thesis we solve the Gross-Pitaevskii equation numerically in order to model the response of trapped Bose-Einstein condensed gases to perturbations by electromagnetic fields. First, we simulate output coupling of pulses from the condensate and compare our results to experiments. The excitation and separation of eigen-modes on flow through a constriction is also studied. We then move on to the main theme of this thesis: the important subject of quantised vortices in Bose condensates, and the relation between Bose-Einstein condensation and superfluidity. We propose methods of producing vortex pairs and rings by controlled motion of objects. Full three-dimensional simulations under realistic experimental conditions are performed in order to test the validity of these ideas. We link vortex formation to drag forces on the object, which in turn is connected with energy transfer to the condensate. We therefore argue that vortex formation by moving objects is intimately related to the onset of dissipation in superfluids. We discuss this idea in the context of a recent experiment, using simulations to provide evidence of vortex formation in the experimental scenario. Superfluidity is also manifest in the property of persistent currents, which is linked to vortex stability and dynamics. We simulate vortex line and ring motion, and find in both cases precessional motion and thermodynamic instability to dissipation. Strictly speaking, the Gross-Pitaevskii equation is valid only for temperatures far below the BEG transition. We end the thesis by describing a simple finite- temperature model to describe mean-field coupling between condensed and non- condensed components of the gas. We show that our hybrid Monte-Carlo/FFT technique can describe damping of the lowest energy excitations of the system. Extensions to this model and future research directions are discussed in the conclusion.