631 research outputs found
Resonances in a trapped 3D Bose-Einstein condensate under periodically varying atomic scattering length
Nonlinear oscillations of a 3D radial symmetric Bose-Einstein condensate
under periodic variation in time of the atomic scattering length have been
studied analytically and numerically. The time-dependent variational approach
is used for the analysis of the characteristics of nonlinear resonances in the
oscillations of the condensate. The bistability in oscillations of the BEC
width is invistigated. The dependence of the BEC collapse threshold on the
drive amplitude and parameters of the condensate and trap is found. Predictions
of the theory are confirmed by numerical simulations of the full
Gross-Pitaevski equation.Comment: 17 pages, 10 figures, submitted to Journal of Physics
Collective excitations of BEC under anharmonic trap position jittering
Collective excitations of a Bose-Einstein condensate under periodic
oscillations of a quadratic plus quartic trap position has been studied. A
coupled set of variational equations is derived for the width and the
condensate wave function center. Analytical expressions for the growth of
oscillation amplitudes in the resonance case are derived. It is shown that
jittering of an anharmonic trap position can cause double resonance of the BEC
width and the center of mass oscillation in the wide range of the BEC
parameters values. The predictions of variational approach are confirmed by
full numerical simulations of the 1D GP equation.Comment: This paper contains a manuscript - SolAnJPB.tex and figures (fig1 -
fig1a.eps and fig1b.eps, fig2 - fig2.eps, fig3 - fig3a.eps and fig3b.eps,
fig4 - fig4a.eps and fig4b.eps). The manuscript has been prepared using
LATEX2e with the iopart class and the figures in encapsulated PostScrip
Stabilization of bright solitons and vortex solitons in a trapless three-dimensional Bose-Einstein condensate by temporal modulation of the scattering length
Using variational and numerical solutions of the mean-field Gross-Pitaevskii
equation we show that a bright soliton can be stabilized in a trapless
three-dimensional attractive Bose-Einstein condensate (BEC) by a rapid periodic
temporal modulation of scattering length alone by using a Feshbach resonance.
This scheme also stabilizes a rotating vortex soliton in two dimensions. Apart
from possible experimental application in BEC, the present study suggests that
the spatiotemporal solitons of nonlinear optics in three dimensions can also be
stabilized in a layered Kerr medium with sign-changing nonlinearity along the
propagation direction.Comment: 6 pages, 7 PS figure
Dissipation-managed soliton in a quasi-one-dimensional Bose-Einstein condensate
We use the time-dependent mean-field Gross-Pitaevskii equation to study the
formation of a dynamically-stabilized dissipation-managed bright soliton in a
quasi-one-dimensional Bose-Einstein condensate (BEC). Because of three-body
recombination of bosonic atoms to molecules, atoms are lost (dissipated) from a
BEC. Such dissipation leads to the decay of a BEC soliton. We demonstrate by a
perturbation procedure that an alimentation of atoms from an external source to
the BEC may compensate for the dissipation loss and lead to a
dynamically-stabilized soliton. The result of the analytical perturbation
method is in excellent agreement with mean-field numerics. It seems possible to
obtain such a dynamically-stabilized BEC soliton without dissipation in
laboratory.Comment: 5 pages, 3 figure
Adiabatic Compression of Soliton Matter Waves
The evolution of atomic solitary waves in Bose-Einstein condensate (BEC)
under adiabatic changes of the atomic scattering length is investigated. The
variations of amplitude, width, and velocity of soliton are found for both
spatial and time adiabatic variations. The possibility to use these variations
to compress solitons up to very high local matter densities is shown both in
absence and in presence of a parabolic confining potential.Comment: to appear in J.Phys.
Free expansion of fermionic dark solitons in a boson-fermion mixture
We use a time-dependent dynamical mean-field-hydrodynamic model to study the
formation of fermionic dark solitons in a trapped degenerate fermi gas mixed
with a Bose-Einstein condensate in a harmonic as well as a periodic
optical-lattice potential. The dark soliton with a "notch" in the probability
density with a zero at the minimum is simulated numerically as a nonlinear
continuation of the first vibrational excitation of the linear
mean-field-hydrodynamic equations, as suggested recently for pure bosons. We
study the free expansion of these dark solitons as well as the consequent
increase in the size of their central notch and discuss the possibility of
experimental observation of the notch after free expansion.Comment: 14 pages, 6 figure
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