497 research outputs found
Liquid-Gas phase transition in Bose-Einstein Condensates
We study the effects of a repulsive three-body interaction on a system of
trapped ultra-cold atoms in a Bose-Einstein condensed state. The corresponding
wave non-linear Schr\"{o}dinger equation is solved numerically and also by
a variational approach. A first-order liquid-gas phase transition is observed
for the condensed state up to a critical strength of the effective three-body
force.Comment: 4 pages, 3 figure
Bose-Hubbard physics in synthetic dimensions from interaction Trotterization
Activating transitions between a set of atomic internal states has emerged as
an elegant scheme by which lattice models can be designed in ultracold atomic
gases. In this approach, the internal states can be viewed as fictitious
lattice sites defined along a synthetic dimension, hence offering a powerful
method by which the spatial dimensionality of the system can be extended.
Inter-particle collisions generically lead to infinite-range interactions along
the synthetic dimensions, which a priori precludes the design of
Bose-Hubbard-type models featuring on-site interactions. In this article, we
solve this obstacle by introducing a protocol that realizes strong and tunable
"on-site" interactions along an atomic synthetic dimension. Our scheme is based
on pulsing strong intra-spin interactions in a fast and periodic manner, hence
realizing the desired "on-site" interactions in a digital (Trotterized) manner.
We explore the viability of this protocol by means of numerical calculations,
which we perform on various examples that are relevant to ultracold-atom
experiments. This general method, which could be applied to various atomic
species by means of fast-response protocols based on Fano-Feshbach resonances,
opens the route for the exploration of strongly-correlated matter in synthetic
dimensions.Comment: 9 pages, 6 figure
Low density expansion and isospin dependence of nuclear energy functional: comparison between relativistic and Skyrme models
In the present work we take the non relativistic limit of relativistic models
and compare the obtained functionals with the usual Skyrme parametrization.
Relativistic models with both constant couplings and with density dependent
couplings are considered. While some models present very good results already
at the lowest order in the density, models with non-linear terms only reproduce
the energy functional if higher order terms are taken into account in the
expansion.Comment: 16 pages,6 figures,5 table
Collective modes in relativistic npe matter at finite temperature
Isospin and density waves in neutral neutron-proton-electron (npe) matter are
studied within a relativistic mean-field hadron model at finite temperature
with the inclusion of the electromagnetic field. The dispersion relation is
calculated and the collective modes are obtained. The unstable modes are
discussed and the spinodals, which separate the stable from the unstable
regions, are shown for different values of the momentum transfer at various
temperatures. The critical temperatures are compared with the ones obtained in
a system without electrons. The largest critical temperature, 12.39 MeV, occurs
for a proton fraction y_p=0.47. For y_p=0.3 we get =5 MeV and for
y_p>0.495 MeV.
It is shown that at finite temperature the distillation effect in asymmetric
matter is not so efficient and that electron effects are particularly important
for small momentum transfers.Comment: 10 pages, 6 figure
New approach of fragment charge correlations in 129Xe+(nat)Sn central collisions
A previous analysis of the charge (Z) correlations in the
plane for Xe+Sn central collisions at 32 MeV/u has shown an enhancement in the
production of equally sized fragments (low ) which was interpreted as
an evidence for spinodal decomposition. However the signal is weak and rises
the question of the estimation of the uncorrelated yield. After a critical
analysis of its robustness, we propose in this paper a new technique to build
the uncorrelated yield in the charge correlation function. The application of
this method to Xe+Sn central collision data at 32, 39, 45 and 50 MeV/u does not
show any particular enhancement of the correlation function in any
bin.Comment: 23 pages, 9 figures, revised version with an added figure and minor
changes. To appear in Nuclear Physics
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