We have obtained spectra of 10 vibrational bands of the Cs₂ (2)³∏_u ← ϰ³∑⁺₉ system. The molecules were formed in a supersonic free jet expansion, and were excited by light from a single mode CW dye laser. The total laser induced fluorescence was measured at 90° to the incident light and molecular beam, using a photomultiplier. Using a slit system to image a selected part of the interaction region, we have reduced the Doppler width to about 350MHz. We have been able to resolve the discrepancy between the different vibrational band positions given in two previous papers. Our vibrational bands show broad rotational contours, but we have not been able to resolve individual rotational lines. We have also obtained rotationally resolved spectra of the bandhead region of 22 vibrational bands of the Β¹∏₉ ← X¹∑⁺_u system. We found that the frequencies of the bandheads agreed with the bandhead positions deduced from the Dunham coefficients of a previous work. We have developed a theoretical model of the rotational structure and intensity distribution, taking into account optical pumping and the small solid angle subtended by the detector. By fitting this model to the experimental spectrum of the v' = 3,u∿ = 0 band using least squares optimization, we were able to extract rotational constants and line positions. We found that these line positions were in good agreement with those from the previous work. We have discussed how such spectroscopic data may be used in a determination of the s-wave scattering length of caesium, and we have reviewed the validity of the scattering length and other pararneterisations of low energy Cs-Cs interactions.

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.

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

Thesis (Ph. D.)--University of Texas at Austin, 2008. / Vita. Includes bibliographical references.

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.

Thesis (Ph. D.)--University of Washington, 2004. / Vita. Includes bibliographical references (p. 127-136).

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

Thesis (Ph. D.)--University of Chicago, Dept. of Physics. / Includes bibliographical references. Also available on the Internet.

Thesis (Ph. D.)--University of Texas at Austin, 2008. / Vita. Includes bibliographical references.

Made available in DSpace on 2014-06-11T19:32:10Z (GMT). No. of bitstreams: 0 Previous issue date: 2013-02-26Bitstream added on 2014-06-13T20:27:16Z : No. of bitstreams: 1 silva_ley_dr_ift.pdf: 4929051 bytes, checksum: ca9589a1164e8d2361903c516c6ac865 (MD5) / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / Nesta tese estudamos conceitos básicos de um condensado de Bose-Einstein (BEC) e sua extensão para sistemas com propriedades mais exóticas, incluindo misturas de dois componentes, com algumas características interessantes encontradas devido à interação entre espécies, e condensados de átomos com forte momento (magnético) dipolar, nos quais a interação dipolo-dipolo (anisotrópica e de longo-alcance), abre novas possibilidades de pesquisa na procura por desconhecidas e fascinantes características para gases atômicos ultra-frios. Mostramos o modelo de campo-médio para misturas de dois BECs interagindo através do potencial de contato e da interação dipolar de longo-alcance empregando termos não lineares de inter e intra-espécies. Aplicamos este modelo em sistemas binários com diferentes armadilhas em que um deles ou ambos podem ser dipolares. Especificamente, estudamos as características físicas de uma mistura de dois BECs - com e sem interação dipolar -, a formação (e dinâmica) de bright solitons para um BEC dipolar, algumas propriedades interessantes para um BEC dipolar no limite de interação forte, e as características de um BEC dipolar quase-livre vinculado à um outro BEC não dipolar confinado numa armadilha magnética. Apresentamos nossos resultados numéricos usando gráficos de densidade, diagramas de fase, de formação de estruturas nas densidades ou a dinâmica dos sistemas, entre outros. Sempre que possível, nossos resultados serão associados com quantidades usadas em técnicas experimentais através de um tipo específico de átomo, o número de partículas, os valores dos parâmetros de interação, a anisotropia da armadilha ou outras quantidades relacionadas com observáveis experimentais / We described the basic ideas of Bose-Einstein condensation (BEC), and then we focused our study on extensions to more exotic condensates including mixtures of two components, where interesting characteristics are found due to the interspecies interaction, and magnetic dipolar gases, which with their ansiotropic long-range dipolar interaction have opened up new avenues of research into cold atoms, in a quest for novel and fascinating features. In this thesis, we present the mean-field model for the binary BEC interacting two-componente mixtures of dipolar and nondipolar BECs, the formation and dynamics of bright solitons, the strong coupling domain for dipolar BECS, and the features of an untrapped bound dipolar droplet in a trapped nondipolar condensate. Our numerical results are presented in density plots, stability, phase plots, structure formartion in densities, breathing oscillation, and more. However, these solutions, whenever possible, are associated with quantities widely handled in experimental techniques, theough a specific types of atoms, number of particles, values of parameters of interaction or the anisotropy of trap, and others quantities related to experimental observables