Quantum Tomography, Wave Packets, and Solitons

The wave packets, both linear and nonlinear (like solitons) signals described by a complex time-dependent function, are mapped onto positive probability distributions (tomograms). The quasidistributions, wavelets, and tomograms are shown to have an intrinsic connection. The analysis is extended to signals obeying to the von Neumann-like equation. For solitons (nonlinear signals) obeying the nonlinear Schrödinger equation, the tomographic probability representation is introduced. It is shown that in the probability representation the soliton satisfies a nonlinear generalization of the Fokker–Planck equation. Solutions to the Gross–Pitaevskii equation corresponding to solitons in a Bose–Einstein condensate are considered.     

Wettability Alteration to Intermediate Gas-Wetting in Porous Media at Elevated Temperatures

Wettability alteration to intermediate gas-wetting in porous media by treatment with FC-759, a fluorochemical polymer has been studied experimentally. Berea sandstone was used as the main rock sample in our work, and its wettability before and after chemical treatment was studied at various temperatures from 25 to 93°C. We also studied recovery performance for both gas/oil and oil/water systems for Berea sandstone before and after wettability alteration by chemical treatment. Our experiment shows that chemical treatment with FC-759 can result in: (1) wettability alteration from strong liquid-wetting to stable intermediate gas-wetting at room temperature and at elevated temperatures; (2) neutral wetting for gas, oil, and water phases in two-phase flow; (3) significant increase in oil mobility for gas/oil system; and (4) improved recovery behavior for both gas/oil and oil/water systems. This work reveals a potential for field application for improved gas-well deliverability and well injectivity by altering the rock wettability around wellbore in gas condensate reservoirs from strong liquid-wetting to intermediate gas-wetting.     

Effect of Hydrogen Sulfide on Condensation and Flow of Gas Condensate Fluids in Porous Media

Condensation and flow experiments were conducted at subsurface conditions in a glass micromodel using reservoir fluids with and without the hydrogen sulfide component. It has been noted that the formation of the condensing phase as well as modes of condensate flow are similar for both fluids. Furthermore, an additional condensate transport mechanism, termed lamella flow, was observed with the sour fluid. It has been concluded that core flow experiments conducted with sweet reservoir fluid should reproduce the flow of sour fluid to a large extent.     

两体和三体相互作用下的非线性Landau-Zener隧穿的圈结构研究

在加速光晶格中玻色-爱因斯坦凝聚体（BEC）,当同时考虑两体和三体相互作用时,其能级结构、隧穿率出现了独特的特性.在一维加速光晶格中的BEC,当两体和三体相互作用参数满足一定条件时,非线性两能级体系的能级结构中出现了圈结构,研究得出了圈的宽度随两体和三体相互作用参数变化的关系,并由此分析圈结构的出现及其大小对BEC隧穿率的影响.     

The spatial behavior of rotating two-component Bose-Einstein condensates

In the understanding of the spatial behavior of interacting components of rotating two-component Bose-Einstein condensates, a central problem is to establish whether coexistence of all the components occurs, or the interspecies interaction leads to extinction, that is, configurations where one or more densities are null. In this paper, we prove that the interspecies interaction leads to extinction in the Thomas-Fermi approximation in dimension three.     

Physical realization and possible identification of topological excitations in quantum Heisenberg anti-ferromagnet on a two dimensional lattice

Physical spin configurations corresponding to topological excitations, expected to be present in the XY limit of a quantum spin 1/2 Heisenberg anti-ferromagnet, are probed on a two dimensional square lattice. Quantum vortices (anti-vortices) are constructed in terms of coherent staggered spin field components, as limiting case of meronic (anti-meronic) configurations. The crucial role of the associated Wess-Zumino-like (WZ-like) term is highlighted in our procedure. The time evolution equation of coherent spin fields used in this analysis is obtained by applying variational principle on the quantum Euclidean action corresponding to the Heisenberg anti-ferromagnet on lattice. It is shown that the WZ-like term can distinguish between vortices and anti-vortices only in a charge sector with odd topological charges. Our formalism is distinctly different from the conventional approach for the construction of quantum vortices (anti-vortices).     

原子的玻色-爱因斯坦凝聚

综述了玻色－－爱因斯坦凝聚（ＢＥＣ）实验研究工作的进展，介绍了玻色－爱因斯坦凝集的概念、形成条件和相关的实验技术，叙述了玻色－爱因斯坦凝集体（ＢＥＣ）和物理性质，展望了发展前景。     

Bosonic loops and gluon condensate

Contributions to the vacuum polarisation inQCD are calculated separately with fermion as well as boson loops to have an idea of results expected for possible supersymmetric extension. It is found that the results are not altered in any significant way.     

Bose-Einstein Condensation and Spontaneous Symmetry Breaking

After recalling briefly the connection between spontaneous symmetry breaking and off-diagonal long-range order for models of magnets a general proof of spontaneous breaking of gauge symmetry as a consequence of Bose-Einstein condensation is presented. The proof is based on a rigorous validation of Bogoliubov's c-number substitution for the k = 0 mode operator α₀.     

Coherent control of ballistic energy growth for a kicked Bose-Einstein condensate

We consider a Bose-Einstein condensate which is split into two momentum components and then “kicked" at the Talbot time by an optical standing wave. The mean energy growth is shown to be suppressed or enhanced depending on the quantum phase between the two momentum components. Experimental verification is provided and we discuss possible implications of our results for recently suggested applications of kicked atoms.