4,218 research outputs found
Stability of giant vortices in quantum liquids
We show how giant vortices can be stabilized in strong external potential
Bose-Einstein condensates. We illustrate the formation of these vortices thanks
to the relaxation Ginzburg-Landau dynamics for two typical potentials in two
spatial dimensions. The giant vortex stability is studied for the particular
case of the rotating cylindrical hard wall. The minimization of the perturbed
energy is simplified into a one dimensional relaxation dynamics. The giant
vortices can be stabilized only in a finite frequency range. Finally we obtain
a curve for the minimum frequency needed to observe a giant vortex for a given
nonlinearity
Transmission and Reflection of Bose-Einstein Condensates Incident on a Gaussian Potential Barrier
We investigate how Bose-Einstein condensates, whose initial state is either
irrotational or contains a single vortex, scatter off a one-dimensional
Gaussian potential barrier. We find that for low atom densities the vortex
structure within the condensate is maintained during scattering, whereas at
medium and high densities, multiple additional vortices can be created by the
scattering process, resulting in complex dynamics and disruption of the atom
cloud. This disruption originates from two different mechanisms associated
respectively with the initial rotation of the atom cloud and the interference
between the incident and reflected matter waves. We investigate how the
reflection probability depends on the vorticity of the initial state and on the
incident velocity of the Bose-Einstein condensate. To interpret our results, we
derive a general analytical expression for the reflection coefficient of a
rotating Bose-Einstein condensate that scatters off a spatially-varying
one-dimensional potential.Comment: 9 pages, 9 figure
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
Dynamics of vortices in weakly interacting Bose-Einstein condensates
We study the dynamics of vortices in ideal and weakly interacting
Bose-Einstein condensates using a Ritz minimization method to solve the
two-dimensional Gross-Pitaevskii equation. For different initial vortex
configurations we calculate the trajectories of the vortices. We find
conditions under which a vortex-antivortex pair annihilates and is created
again. For the case of three vortices we show that at certain times two
additional vortices may be created, which move through the condensate and
annihilate each other again. For a noninteracting condensate this process is
periodic, whereas for small interactions the essential features persist, but
the periodicity is lost. The results are compared to exact numerical solutions
of the Gross-Pitaevskii equation confirming our analytical findings.Comment: 8 pages, 7 figures, one reference updated, typos correcte
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