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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
181

Double-TOP trap for ultracold atoms

Thomas, Nicholas, n/a January 2005 (has links)
The Double-TOP trap is a new type of magnetic trap for neutral atoms, and is suitable for Bose-Einstein condensates (BECs) and evaporatively cooled atoms. It combines features from two other magnetic traps, the Time-averaged Orbiting Potential (TOP) and Ioffe-Pritchard traps, so that a potential barrier can be raised in an otherwise parabolic potential. The cigar-like cloud of atoms (in the single-well configuration) is divided halfway along its length when the barrier is lifted. A theoretical model of the trap is presented. The double-well is characterised by the barrier height and well separation, which are weakly coupled. The accessible parameter space is found by considering experimental limits such as noise, yielding well separations from 230 [mu]m up to several millimetres, and barrier heights from 65 pK to 28 [mu]K (where the energies are scaled by Boltzmann�s constant). Potential experiments for Bose-Einstein condensates in this trap are considered. A Double-TOP trap has been constructed using the 3-coil style of Ioffe-Pritchard trap. Details of the design, construction and current control for these coils are given. Experiments on splitting thermal clouds were carried out, which revealed a tilt in the potential. Two independent BECs were simultaneously created by applying evaporative cooling to a divided thermal cloud. The Double-TOP trap is used to form a linear collider, allowing direct imaging of the interference between the s and d partial waves. By jumping from a double to single-well trap configuration, two ultra-cold clouds are launched towards a collision at the trap bottom. The available collision energies are centred on a d-wave shape resonance so that interference between the s and d partial waves is pronounced. Absorption imaging allows complete scattering information to be collected, and the images show a striking change in the angular distribution of atoms post-collision. The results are compared to a theoretical model, verifying that the technique is a useful new way to study cold collisions.
182

On the one-dimensional bose gas

Makin, Melissa I. Unknown Date (has links) (PDF)
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.
183

Optical trapping and manipulation of atoms near surfaces

Cornelussen, Ronald Alexander. January 2004 (has links)
Proefschrift Universiteit van Amsterdam. / Met lit. opg. - Met samenvatting in het Nederlands.
184

A theoretical study of strongly interacting superfluids and superconductors

Sensarma, Rajdeep. January 2007 (has links)
Thesis (Ph. D.)--Ohio State University, 2007. / Title from first page of PDF file. Includes bibliographical references (p. 187-192).
185

Quantum theory of many Bose atom systems /

Khan, Imran. January 2007 (has links)
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.
186

Exceptional points in atomic spectra and Bose-Einstein condensates

Cartarius, Holger, January 2008 (has links)
Stuttgart, Univ., Diss., 2008.
187

Exitonic condensation in bilayer systems

Su, Jung-Jung. January 1900 (has links)
Thesis (Ph. D.)--University of Texas at Austin, 2008. / Vita. Includes bibliographical references.
188

Classical and quantum field theory of Bose-Einstein condensates /

Wüster, Sebastian. January 2007 (has links)
Thesis (Ph.D) -- Australian National University, 2007. / DVD contains movies in .mov (macintosh quicktime) and .mpg formats, providing additional visualisation of the material discussed in the thesis. It also contains the source files for figures within the thesis as well as sample numerical code that was used for the research. The accompanying .txt files provide a brief description of the movie and a link to the relevant part of the thesis. Also contains some files in pdf format.
189

Mean field and correlated descriptions of Bose-Einstein condensates /

Mahmud, Khan W. January 2004 (has links)
Thesis (Ph. D.)--University of Washington, 2004. / Vita. Includes bibliographical references (p. 127-136).
190

Dynamics of Bose-Einstein condensates in optical lattices /

McKinney, Sarah. January 2004 (has links)
Thesis (Ph. D.)--University of Washington, 2004. / Vita. Includes bibliographical references (p. 125-134).

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