361 research outputs found
Vortices and turbulence in trapped atomic condensates
After over a decade of experiments generating and studying the physics of
quantized vortices in atomic gas Bose-Einstein condensates, research is
beginning to focus on the roles of vortices in quantum turbulence, as well as
other measures of quantum turbulence in atomic condensates. Such research
directions have the potential to uncover new insights into quantum turbulence,
vortices and superfluidity, and also explore the similarities and differences
between quantum and classical turbulence in entirely new settings. Here we
present a critical assessment of theoretical and experimental studies in this
emerging field of quantum turbulence in atomic condensates
Comment on "Bose-Einstein condensation in low-dimensional traps"
We show that the critical temperature of a one-dimensional gas confined by a
power-law potential should be lower than that in the paper of Vanderlei Bagnato
and Daniel Kleppner. Moreover, a sketch of the critical temperature is given in
some more details.Comment: 2 pages, 1 eps figure. to appear in Phys. Rev.
Análogo mecânico para a condutividade elétrica dos metais : efeitos da temperatura
Electrical conductivity is one of the most important concepts within aspects of modern physics with a great extension to materials science. It is responsible for most applications of metallic and semiconductor materials. The understanding of microscopic models that reproduce certain characteristics is an important step towards the understanding of materials. In this work we continue to use a system that constitutes a mechanical analogue to understand how the limitations of electrical conductivity of metals occur. Using this model we investigated the effect of temperature on conductivity. The model presented here is quite instructive and lends itself very well to demonstrations in the classroom or even for carrying out laboratory practices in undergraduate courses or teaching practices in Physics in High School
Simple analysis of off-axis solenoid fields using the scalar magnetostatic potential: application to a Zeeman-slower for cold atoms
In a region free of currents, magnetostatics can be described by the Laplace
equation of a scalar magnetic potential, and one can apply the same methods
commonly used in electrostatics. Here we show how to calculate the general
vector field inside a real (finite) solenoid, using only the magnitude of the
field along the symmetry axis. Our method does not require integration or
knowledge of the current distribution, and is presented through practical
examples, including a non-uniform finite solenoid used to produce cold atomic
beams via laser cooling. These examples allow educators to discuss the
non-trivial calculation of fields off-axis using concepts familiar to most
students, while offering the opportunity to introduce important advancements of
current modern research.Comment: 6 pages. Accepted in the American Journal of Physic
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