184 research outputs found
Spinor BECs in a double-well: population transfer and Josephson oscillations
The dynamics of an F=1 spinor condensate in a two-well potential is studied
within the framework of the Gross-Pitaevskii equation. We derive two-mode
equations relating the population imbalances, the phase differences among the
condensates at each side of the barrier and the time evolution of the different
Zeeman populations for the case of small population imbalances. The case of
zero total magnetization is scrutinized in this limit demonstrating the ability
of a two mode analysis to describe to a large extent the dynamics observed in
the Gross-Pitaevskii equations. It is also demonstrated that the time evolution
of the different total populations fully decouples from the Josephson tunneling
phenomena. All the relevant time scales are clearly identified with microscopic
properties of the atom-atom interactions
Spin mixing in colliding spinor condensates: formation of an effective barrier
The dynamics of F=1 spinor condensates initially prepared in a double-well
potential is studied in the mean field approach. It is shown that a small seed
of atoms on a system with initially well separated m=1 and m=-1
condensates has a dramatic effect on their mixing dynamics, acting as an
effective barrier for a remarkably long time. We show that this effect is due
to the spinor character of the system, and provides an observable example of
the interplay between the internal spin dynamics and the macroscopic evolution
of the magnetization in a spinor Bose-Einstein condensate.Comment: Accepted for publication at the Europhysics Letter
Hyperon effects on the properties of -stable neutron star matter
We present results from Brueckner-Hartree-Fock calculations for
-stable neutron star matter with nucleonic and hyperonic degrees of
freedom employing the most recent parametrizations of the baryon-baryon
interaction of the Nijmegen group. Only and are present up
to densities . The corresponding equations of state are then used
to compute properties of neutron stars such as masses and radii.Comment: 4 pages, contributed talk at HYP2000, Torino, 23-27 Oct. 200
Predicting spinor condensate dynamics from simple principles
We study the spin dynamics of quasi-one-dimensional F=1 condensates both at
zero and finite temperatures for arbitrary initial spin configurations. The
rich dynamical evolution exhibited by these non-linear systems is explained by
surprisingly simple principles: minimization of energy at zero temperature, and
maximization of entropy at high temperature. Our analytical results for the
homogeneous case are corroborated by numerical simulations for confined
condensates in a wide variety of initial conditions. These predictions compare
qualitatively well with recent experimental observations and can, therefore,
serve as a guidance for on-going experiments.Comment: 4 pages, 2 figures. v3: matches version appeared in PR
High-momentum proton removal from 16O and the (e,e'p) cross section
The cross section for the removal of high-momentum protons from 16O is
calculated for high missing energies. The admixture of high-momentum nucleons
in the 16O ground state is obtained by calculating the single-hole spectral
function directly in the finite nucleus with the inclusion of short-range and
tensor correlations induced by a realistic meson-exchange interaction. The
presence of high-momentum nucleons in the transition to final states in 15N at
60-100 MeV missing energy is converted to the coincidence cross section for the
(e,e'p) reaction by including the coupling to the electromagnetic probe and the
final state interactions of the outgoing proton in the same way as in the
standard analysis of the experimental data. Detectable cross sections for the
removal of a single proton at these high missing energies are obtained which
are considerably larger at higher missing momentum than the corresponding cross
sections for the p-wave quasihole transitions. Cross sections for these
quasihole transitions are compared with the most recent experimental data
available.Comment: 26 RevTex pages, 7 ps figure
Los reptiles del prepirineo oriental (Cadí-Moixeró y La Cerdaña) y biogeografia de la herpetofauna de la zona
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