7,757 research outputs found
Signatures of Bose-Einstein condensation in an optical lattice
We discuss typical experimental signatures for the Bose-Einstein condensation
(BEC) of an ultracold Bose gas in an inhomogeneous optical lattice at finite
temperature. Applying the Hartree-Fock-Bogoliubov-Popov formalism, we calculate
quantities such as the momentum-space density distribution, visibility and peak
width as the system is tuned through the superfluid to normal phase transition.
Different from previous studies, we consider systems with fixed total particle
number, which is of direct experimental relevance. We show that the onset of
BEC is accompanied by sharp features in all these signatures, which can be
probed via typical time-of-flight imaging techniques. In particular, we find a
two-platform structure in the peak width across the phase transition. We show
that the onset of condensation is related to the emergence of the higher
platform, which can be used as an effective experimental signature.Comment: 5 pages, 3 figure
A Note on Symplectic, Multisymplectic Scheme in Finite Element Method
We find that with uniform mesh, the numerical schemes derived from finite
element method can keep a preserved symplectic structure in one-dimensional
case and a preserved multisymplectic structure in two-dimentional case in
certain discrete version respectively. These results are in fact the intrinsic
reason that the numerical experiments indicate that such finite element
algorithms are accurate in practice.Comment: 7 pages, 3 figure
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