939 research outputs found
Mesoscopic ensembles of polar bosons in triple-well potentials
Mesoscopic dipolar Bose gases in triple-well potentials offer a minimal
system for the analysis of the long-range character of the dipole-dipole
interactions. We show that this long-range character may be clearly revealed by
a variety of possible ground-state phases. In addition, an appropriate control
of short-range and dipolar interactions may lead to novel scenarios for the
dynamics of atoms and polar molecules in lattices, including the dynamical
creation of mesoscopic Schr\"odinger cats, which may be employed as a source of
highly-nonclassical states for Heisenberg-limited interferometry.Comment: 4 pages, 3 figures. Identical to the published version, including
supplemental material (4 pages, 6 figures)
Strongly Correlated States of Ultracold Rotating Dipolar Fermi Gases
We study strongly correlated ground and excited states of rotating quasi-2D
Fermi gases constituted of a small number of dipole-dipole interacting
particles with dipole moments polarized perpendicular to the plane of motion.
As the number of atoms grows, the system enters {\it an intermediate regime},
where ground states are subject to a competition between distinct bulk-edge
configurations. This effect obscures their description in terms of composite
fermions and leads to the appearance of novel composite fermion quasi-hole
states. In the presence of dipolar interactions, the principal Laughlin state
at filling exhibits a substantial energy gap for neutral (total
angular momentum conserving) excitations, and is well-described as an
incompressible Fermi liquid. Instead, at lower fillings, the ground state
structure favors crystalline order.Comment: 5 pages, 5 figures, paper presented at DPG Meeting 2006, as well as
Fritz Haber Institute Colloquiu
Discrete-step evaporation of an atomic beam
We present a theoretical analysis of the evaporative cooling of a
magnetically guided atomic beam by means of discrete radio-frequency antennas.
First we derive the changes in flux and temperature, as well as in collision
rate and phase-space density, for a single evaporation step. Next we show how
the occurrence of collisions during the propagation between two successive
antennas can be probed. Finally, we discuss the optimization of the evaporation
ramp with several antennas to reach quantum degeneracy. We estimate the number
of antennas required to increase the phase-space density by several orders of
magnitude. We find that at least 30 antennas are needed to gain a factor
in phase-space density.Comment: Submitted to Eur. Phys. J.
Low-energy resonances and bound states of aligned bosonic and fermionic dipoles
The low-energy scattering properties of two aligned identical bosonic and
identical fermionic dipoles are analyzed. Generalized scattering lengths are
determined as functions of the dipole moment and the scattering energy. Near
resonance, where a new bound state is being pulled in, all non-vanishing
generalized scattering lengths diverge, with the and
scattering lengths being dominant for identical bosons and identical fermions,
respectively, near both broad and narrow resonances. Implications for the
energy spectrum and the eigenfunctions of trapped two-dipole systems and for
pseudo-potential treatments are discussed.Comment: 4 pages, 4 figure
Transport of Atom Packets in a Train of Ioffe-Pritchard Traps
We demonstrate transport and evaporative cooling of several atomic clouds in
a chain of magnetic Ioffe-Pritchard traps moving at a low speed (~m/s). The
trapping scheme relies on the use of a magnetic guide for transverse
confinement and of magnets fixed on a conveyor belt for longitudinal trapping.
This experiment introduces a new approach for parallelizing the production of
Bose-Einstein condensates as well as for the realization of a continuous atom
laser
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