Matter wave switching in Bose-Einstein condensates via intensity redistribution soliton interactions

Using time dependent nonlinear (s-wave scattering length) coupling between the components of a weakly interacting two component Bose-Einstein condensate (BEC), we show the possibility of matter wave switching (fraction of atoms transfer) between the components via shape changing/intensity redistribution (matter redistribution) soliton interactions. We investigate the exact bright-bright N-soliton solution of an effective one-dimensional (1D) two component BEC by suitably tailoring the trap potential, atomic scattering length and atom gain or loss. In particular, we show that the effective 1D coupled Gross-Pitaevskii (GP) equations with time dependent parameters can be transformed into the well known completely integrable Manakov model described by coupled nonlinear Schr\"odinger (CNLS) equations by effecting a change of variables of the coordinates and the wave functions under certain conditions related to the time dependent parameters. We obtain the one-soliton solution and demonstrate the shape changing/matter redistribution interactions of two and three soliton solutions for the time independent expulsive harmonic trap potential, periodically modulated harmonic trap potential and kink-like modulated harmonic trap potential. The standard elastic collision of solitons occur only for a specific choice of soliton parameters.Comment: 11 pages, 14 figures, 1 tabl

Reconstructing the Earthquake Recurrence Pattern in the Central Himalaya: Evidence from the Himalayan Frontal Thrust

Abstract HKT-ISTP 2013 A

Development of stereoscopic particle tracking velocimetry for turbulent flow field diagnostics

Stereoscopic particle tracking velocimetry (SPTV) was used to analyze a turbulent submerged jet of Reynolds number (based on the diameter of the nozzle) 8000. SPTV involves tracking the motion of tracer particles over time in a flow in three dimensions. The first part of this work consisted of developing a stereoscopic particle tracking technique using two high-speed video cameras. This included calibration of the cameras with known points, and developing an algorithm to automatically match and track particles. The second part was to apply the same to a submerged water jet in order to measure velocities. The velocities were subsequently used to calculate the components of the Reynolds stress tensor, vorticities and other useful turbulent parameters in all three directions at two locations along the axis of the jet. The cameras were calibrated using a set of known grid points which were imaged by both cameras. Data reduction equations, that relate the world coordinates (X, Y, Z positions in space) of the object (grid) points to their image coordinates in left and right cameras, were solved to obtain a set of modified camera parameters. The uncertainties in determining the X, Y and Z positions of the grid points, after correcting for the bias errors due to refraction and lens distortion, were found to be 6.81 x 10-5mm, 5.84 x 10-5 mm and 1.73 x 10-4 mm respectively in a 19mm x 27mm x 19mm measurement volume. Calibration and measurements were performed at two downstream locations along the axis of the jet. The corresponding measurement volumes were centered at ten and twenty nozzle diameters from the nozzle exit (x/d≡10 and 20). Polystyrene particles of 250 μm size were used to visualize the flow. A matching and tracking algorithm was developed to automatically find corresponding particles in the two views, and to track them into the next time step. Image coordinates of the particles in the stereo views were used to calculate the world coordinates of the particle. Velocities were calculated knowing the particle displacements and the elapsed time. Particle data for 100 time steps (total duration of 50 ms at x/d≡10; and 100 ms at x/d≡20) were pooled. The mean and fluctuating components of velocities were found and all components of the Reynolds stress tensor (u\u272, v\u272, w\u272, u\u27v\u27, v\u27w\u27, w\u27u\u27) were calculated. The vorticity field in the vertical (X-Y) plane of the jet was calculated. Integral scales were also calculated across the jet. Turbulent microscales in longitudinal and lateral directions were estimated based on the velocity fluctuations and their gradients. The mean velocity profile at x/d=22 was found to be in good agreement with the Görtler type analytical solution for the submerged round jet. A possible mechanism by which bubbles injected into the turbulent flow field undergo deformation, which may result in oscillations, was suggested. The main causes of errors in the measurement and in the particle data analysis were discussed. Possible remedies were suggested

Research Output of Greenhouse Effect in India: A Scientometric Analysis

The research Article presents a Scientometric analyst of research output in India in the field of Greenhouse Effect during the period of 2001 to 2017 as reflected in SCOPUS Database. Collected data for a total of 568 have been published in India in the field of Greenhouse effect and it’s analyzed according to objectives. The research paper reveal that the year wise growth of literature in terms of year wise growth in the number of publications, subject areas leading to maximum publications, international affiliations, relative growth rate, doubling time and the individual contributions of authors to name a few and their publication reveals that Tiwari, G.N published highest number of papers 21 (3.70%), Document Wise Distribution show that the most number of documents are of the type article totaling to 395 (69.54%) publications. Foreign Countries Contribution in India shows that The United States of America (USA) has the top rate of involvement with 60 (31.91%)

Interaction of dark-bright solitons in two-component Bose-Einstein condensates

We study the interaction of dark-bright solitons in two component Bose-Einstein condensates by suitably tailoring the trap potential, atomic scattering length and atom gain or loss. We show that the coupled Gross-Pitaevskii (GP) equation can be mapped onto the Manakov model. An interesting class of matter wave solitons and their interaction are identified with time independent and periodically modulated trap potentials, which can be experimentally realized in two component condensates. These include periodic collapse and revival of solitons, and snake-like matter wave solitons as well as different kinds of two soliton interactions.Comment: 10 pages, 5 figure