Dynamics of Macroscopic Tunneling in Elongated BEC

We investigate macroscopic tunneling from an elongated quasi 1-d trap, forming a 'cigar shaped' BEC. Using recently developed formalism we get the leading analytical approximation for the right hand side of the potential wall, i.e. outside the trap, and a formalism based on Wigner functions, for the left side of the potential wall, i.e. inside the BEC. We then present accomplished results of numerical calculations, which show a 'blip' in the particle density traveling with an asymptotic shock velocity, as resulted from previous works on a dot-like trap, but with significant differences from the latter. Inside the BEC a pattern of a traveling dispersive shock wave is revealed. In the attractive case, we find trains of bright solitons frozen near the boundary.Comment: 6 pages, 15 figure

Jet-like tunneling from a trapped vortex

We analyze the tunneling of vortex states from elliptically shaped traps. Using the hydrodynamic representation of the Gross-Pitaevskii (Nonlinear Schr\"odinger) equation, we derive analytically and demonstrate numerically a novel type of quantum fluid flow: a jet-like singularity formed by the interaction between the vortex and the nonhomogenous field. For strongly elongated traps, the ellipticity overwhelms the circular rotation, resulting in the ejection of field in narrow, well-defined directions. These jets can also be understood as a formation of caustics since they correspond to a convergence of trajectories starting from the top of the potential barrier and meeting at a certain point on the exit line. They will appear in any coherent wave system with angular momentum and non-circular symmetry, such as superfluids, Bose-Einstein condensates, and light.Comment: 4 pages, 4 figure

Image of the Scientist in Context of Comparison of the German and Israeli Scientific Mediadiscourse in the Field of Research in Quantum Nanotechnologies (on Materials of Magazines «Max Planck Forschung» and «Technion» from 2007 to 2017)

Статья основана на сравнении немецкого и израильского медиадискурса в области исследования квантовых нанотехнологий. В рассматриваемых журнальных материалах выявлено, что амплитуда развития научных интересов в обеих странах вызвана потребностью каждого из государств. В ходе анализа темы конструируется образ ученого, проявляющего типичные для представителей научного сообщества черты. Индивидуальный образ ученого можно представить как исследователя, работающего в авангарде науки на стыке междисциплинарности и развивающего традиции своей научной школы. Формирование такого образа способствует повышению престижа профессии ученого в сфере квантовых нанотехнологий.The paper is based on a comparison of German and Israeli media discourse in the field of research in quantum nanotechnologies. In these magazines it is revealed that the amplitude of development of scientific interests in both countries depends on the needs of each state. Analysis of the topic the image of a scientist is constructed, who shows features typical for representatives of the scientific community. The individuals’ image of nano-scientists can be generally abstracted as a researcher who works at the forefront of science at the intersection of interdisciplinarity and develops the traditions of his scientific school. The formation of such an image contributes to increasing the prestige of the scientist's profession in the field of quantum nanotechnology

Dynamics of fluctuations in an optical analog of the Laval nozzle

Using the analogy between the description of coherent light propagation in a medium with Kerr nonlinearity by means of nonlinear Schr\"odinger equation and that of a dissipationless liquid we propose an optical analogue of the Laval nozzle. The optical Laval nozzle will allow one to form a transonic flow in which one can observe and study a very unusual dynamics of classical and quantum fluctuations including analogue of the Hawking radiation of real black holes. Theoretical analysis of this dynamics is supported by numerical calculations and estimates for a possible experimental setup are presented.Comment: 7 pages, 4 figure

Nonlinear Dynamic Phenomena in Macroscopic Tunneling

Numerical simulations of the NLSE (or GPE) are presented demonstrating emission of short pulses of the matter (light) density formed in the course of tunneling in wave-guided light and/or trapped BEC. The phenomenon is observed under various conditions, for nonlinearities of different signs, zero nonlinearity included. We study, both numerically and analytically, pulsations of matter (light) remaining within the trap and use the results in order to induce emission of sequential pulses by properly narrowing the trap. This allows us to propose a mechanism for a realization of Atom Pulse Laser.Comment: 14 pages, 6 figure