35,893 research outputs found
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
Delayed fracture of titanium alloys
Delayed fracture tests and brittle properties of titanium aluminum zirconium allo
Is really related to the solar neutrino solutions?
It has been said that the measurements of in the lepton flavor
mixing matrix would help discriminate between the possible solar neutrino
solutions under the natural conditions with the neutrino mass hierarchies of
and , where is the -th
generation neutrino absolute mass. However, it is not true, and the relation
between and obtained by Akhmedov, Branco, and
Rebelo is trivial in actual. We show in this paper that the value of
cannot predict the solar neutrino solutions without one additional nontrivial
condition.Comment: 7pages, no figur
Stable localized modes in asymmetric waveguides with gain and loss
It is shown that asymmetric waveguides with gain and loss can support a
stable propagation of optical beams. This means that the propagation constants
of modes of the corresponding complex optical potential are real. A class of
such waveguides is found from a relation between two spectral problems. A
particular example of an asymmetric waveguide, described by the hyperbolic
functions, is analyzed. The existence and stability of linear modes and of
continuous families of nonlinear modes are demonstrated.Comment: 10 pages, 4 figures. Accepted in Optics Letters, 201
Accretion disk around the rotating Damour-Solodukhin wormhole
A new rotating generalization of the Damour-Solodukhin wormhole (RDSWH),
called Kerr-like wormhole, has recently been proposed and investigated by Bueno
\textit{et al} for echoes in the gravitational wave signal. We show a novel
feature of the RDSWH, viz., that the kinematic properties such as the ISCO\ or
marginally stable radius , efficiency and the disk
potential are \textit{independent} of (which means
they are identical to their KBH counterparts for any given spin). Differences
however appear in the emissivity properties for higher values (say) and for the extreme spin . The kinematic and
emissivity are generic properties as variations of the wormhole mass and the
rate of accretion within the model preserve these properties. Specifically, the
behavior of the luminosity peak is quite opposite to each other for the two
objects, which could be useful from the viewpoint of observations. Apart from
this, an estimate of the difference in the maxima of flux of
radiation shows non-zero values but is too tiny to be observable at
present for permitted by the strong lensing bound. The
broad conclusion is that RDSWH\ are experimentally indistinguishable from KBH
by accretion characteristics.Comment: 9 pages, 3 tables, 13 figure
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
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