Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 99 for “"BEC"”.
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The BCS - BEC Crossover in Ultracold Fermion Gases
… of fermion pairs and a Bose-Einstein condensate (BEC) of tightly bound bosonic molecules can be attributed to the spontaneous breaking of global $U(1)$ gauge symmetry which underlies both quantum condensation phenomena. Recently much attention has been paid to this problem, since Feshbach …
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Coherent micromanipulation of 1-D BEC in designed potentials
… create and address a Bose-Einstein condensate (BEC) is the atomchip: A lithographycally patterned surface on which gold conductors are used to generate magnetic fields. To fully realize what the atomchip has to offer the miniaturization of structures and the integration of different devices …
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BEC-BCS crossover with Feshbach resonance for three-hyperfine-species model
The BEC-BCS crossover problem has been intensively studied both theoretically and experimentally largely thanks to Feshbach resonances which allow us to tune the effective interaction between alkali atoms. In a Feshbach resonance, the effective s-wave scattering length grows when one moves toward …
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Mean-field theory for the dynamics of superfluid fermions in the BCS-BEC crossover
We use mean-field theory to investigate the dynamics of superfluid fermions. This thesis includes our two works. The first one is to study Josephson oscillations and self-trapping of superfluid fermions in a double-well potential with time-dependent Bogoliubov-de Gennes equations. We investigate …
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Pairing and Superfluid Properties of Polarized Dilute Fermion Gases in the Bcs-Bec Crossover
We then consider systems in which the pairing species have different chemical potentials, imposed in our case, with different number densities, leading to a finite 'polarization'. This is of much experimental and theoretical interest due to the number of exotic ground states that have been …
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1S-2S spectroscopy of trapped hydrogen : the cold collision frequency shift and studies of BEC
Thesis (Ph.D.)--Massachusetts Institute of Technology, Dept. of Physics, 1999.
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Role of BEC-1/Beclin 1 and Autophagy Genes in <i>C.elegans</i> Germline Cell Proliferation
… cell-autonomously. Here we evaluate the role of BEC-1 and autophagy gene function in cell proliferation, using the <em>C. elegans</em> germ line as an <em>in vivo</em> model. BEC-1 is the <em>C. elegans</em> ortholog of human BECN1/Beclin 1, an essential autophagy regulator and tumor suppressor …
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Study of Ultracold Fermi Gases in the BCS-BEC Crossover: Quantum Monte Carlo Methods, Hydrodynamics and Local Density Approximation.
… to Bose-Einstein-Condensation (BCS-BEC) crossover in two dimensions. We use DFT in the Local Density Approximation (LDA) for calculating the density profiles of ultracold Fermi gases in harmonic magneto-optical traps, starting from QMC equations of state. We study the propagation of …
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Mechanisms of methylenedianiline toxicity to rat biliary epithelial cells
… rapidly injures biliary epithelial cells (BEC) of rats in vivo. DAPM also increases biliary inorganic phosphate and glucose, suggesting that DAPM loosens hepatic tight junctions. Early ultrastructural alterations in BEC mitochondria, however, suggested a possible role of mitochondrial …
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Evaluation of the World Health Organization’s basic emergency care course and online cases in Uganda
… Organization’s (WHO) Basic Emergency Care (BEC) course, the first openaccess short course to provide comprehensive basic emergency training for health workers in low-resource settings. The BEC and its new online cases both require further evaluation. Aim and Objectives The study aimed to …
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The dynamics of ultracold atoms in light-induced synthetic gauge fields
… ultracold atoms to the Bose-Einstein condensate (BEC) phase. We implement a model of atomic evaporation in a trapping potential, and we find optimal parameters for the trap depth and stiffness during evaporation. Using this model, we achieve a high efficiency of optical evaporation (γ<sub> …
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Transport properties of a Bose-Einstein condensate with tunable interactions in the presence of a disordered or single defect potential
Bose-Einstein condensates (BECs) have proven to be remarkable systems with which to study some of the foundational models of condensed matter physics. The observation of a critical velocity for the breakdown of superfluidity in a BEC and the superfluid to Mott insulator transition observed in a BEC …
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Effects of interaction in Bose-Einstein condensates
… various properties of Bose-Einstein condensates (BEC). The phonon wavefunction in a BEC was measured using Bragg spectroscopy and compared with the well-known Bogoliubov theory. Phonons were first excited in a BEC of 3 x 107 condensed 23Na atoms via small-angle two-photon Bragg scattering. Large …
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Do Characteristics of the Built Environment Influence Walking Behaviour Among Urban Adults? A Conceptual Framework, Systematic Review, and Research Plan
… between built environment characteristics (BECs) and walking, synthesize evidence on associations, and propose future research that addresses limitations in existing studies. I designed a conceptual framework of hypothesized BEC - walking associations. I conducted a systematic review, …
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Dynamics of finite momentum Bose polarons
… a weakly interacting Bose-Einstein condensate (BEC) of ultra-cold atoms near an interspecies Feshbach resonance. Using the time-dependent variational approach, we study both ground state properties and quench dynamics of the system after a sudden immersion of the impurity into the BEC. We find …
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Atoms and Molecules Immersed in a Bose-Einstein Condensate
… length are long-lived in the presence of the BEC. We demonstrate direct photoassociation from Bose polarons to electron- ically excited molecular states, dark resonance spectroscopy of the absolute ground state molecular state, and finally stimulated rapid adiabatic passage (STIRAP) of Bose …
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Solitons in Magnetic Systems
… in the field of Bose-Einstein condensate (BEC) mixtures, with its main focus on the dynamics of solitary waves in such systems in conditions of broken integrability and with reference to the formal and physical analogies between BEC mixtures and the classical magnetization dynamics of …
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High contrast interferometry and finite temperature coherence of Bose-Einstein condensates
… results of a Bose-Einstein condensate(BEC) interferometer and the finite temperature coherence of elongated BECs. Cold atom and BEC-based interferometers take advantage of the wave nature of atoms as they are cooled and can be used for precision measurements of fundamental physics, …
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Strongly-interacting fermions in an optical lattice
… conducted with sodium Bose-Einstein condensates (BEC) while the second focuses on the pairing of fermionic lithium-6 pairs in an optical lattice within the strongly interacting BEC-BCS regime. Common to both sets of studies is the use of a magnetically tunable Feshbach resonance to manipulate …
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One-dimensional Bose-Einstein condensates in micro-traps
… been achieved. The Bose-Einstein condensates (BECs) created in the micro-traps form in the one-dimensional Thomas-Fermi regime. The cross-over between three-dimensional and one-dimensional BECs has been investigated by monitoring the transverse size of the BEC after ballistic expansion. Good …
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