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Soliton and Landau-Zener Tunneling Dynamics of Bose-Einstein Condensates Trapped in optical Lattices

Author: ZuoYuDong
Tutor: WangDengLong
School: Xiangtan University
Course: Atomic and Molecular Physics
Keywords: Bose - Einstein condensates Optical lattice potential well Soliton Landau-Zener tunneling Gross-Pitaevskii equation
CLC: O431.2
Type: Master's thesis
Year: 2009
Downloads: 104
Quote: 0
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Abstract


Bose - Einstein condensate (BEC) has been successfully loaded in the optical lattice potential well, which is similar to solid state physics electrons are bound to the solid lattice confined to an optical lattice potential well BEC some physical properties similar to the interaction of the electrons with the lattice. BEC atoms confined to light-induced periodic potential well (optical potential well) not only has many of the properties of electrons in solids, but also have the fluctuating nature of the nonlinear material and nonlinear system, so researchers research interest. Recently, experiments have been successfully loaded ultra-cold boson external potential well of a two-color optical lattice, two-color optical lattice consists of two pairs of laser beams, the wavelength of the laser beam and the second laser beam wavelength different, but the two on the intensity of the laser beam can be from weak to strong regulation. Therefore, the study limited to monochrome or two-color optical lattice potential well of BEC solitons and the Landau-Zener tunneling behavior with certain basic meaning. Gross Pitaevskii (GP) equation from the mean field theory, the first use of multi-scale method to study analytically limited to monochromatic light lattice potential well and harmonic trap composite potential well BEC soliton dynamics behavior , followed by the use of numerical methods to study the two-color optical lattice potential well BEC Landau-Zener tunneling properties. The main structure is as follows: The first chapter describes the basic knowledge of the BEC, the description of the the BEC dynamics behavior of the GP equation is derived based on the mean-field approximation theory. Currently limited to optical lattice BEC research development and research significance. Based on experimental achieve BEC in the optical lattice potential well, in the second chapter, the use of multiple scales method combined with the Wentzel-Kramer-Brillouin expand, we study analytically confined to an optical lattice potential well and harmonic trap consisting of composite potential well BEC soliton dynamics behavior. The results show that, due to the periodic potential modulation effects, BEC dark soliton evolved into a gray soliton. Meanwhile, with the increase in the strength of periodic potential, reduce the speed of the soliton increase the width is reduced, and there is a minimum value. Similarly, since the two-color optical lattice formed by two coherent laser potential well in the third chapter, we numerically studied two-color optical lattice potential well BEC atoms Landau-Zener tunneling behavior. The results show that with the main two-color optical lattice potential well, sub-lattice phase difference (?) Bloch energy band energy gap gradually increased from 0 to pi, and the second band gap gradually decreases . Also found that two-color optical lattice potential well, the primary and secondary lattice depth and the phase difference of the first energy gap and the second gap Landau-Zener tunneling properties has important implications. Finally, in the fourth chapter of this work is a simple summary of the Next forthcoming work.

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CLC: > Mathematical sciences and chemical > Physics > Optics > The light nature of the theory > Quantum optics
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