95 research outputs found
Ion induced density bubble in a strongly correlated one dimensional gas
We consider a harmonically trapped Tonks-Girardeau gas of impenetrable bosons
in the presence of a single embedded ion, which is assumed to be tightly
confined in a RF trap. In an ultracold ion-atom collision the ion's charge
induces an electric dipole moment in the atoms which leads to an attractive
potential asymptotically. We treat the ion as a static deformation of
the harmonic trap potential and model its short range interaction with the gas
in the framework of quantum defect theory. The molecular bound states of the
ionic potential are not populated due to the lack of any possible relaxation
process in the Tonks-Girardeau regime. Armed with this knowledge we calculate
the density profile of the gas in the presence of a central ionic impurity and
show that a density \textit{bubble} of the order of a micron occurs around the
ion for typical experimental parameters. From these exact results we show that
an ionic impurity in a Tonks gas can be described using a pseudopotential,
allowing for significantly easier treatment.Comment: Accepted for publication in Physical Review A (Rapid Communications)
Two atoms in an anisotropic harmonic trap
We consider the system of two interacting atoms confined in axially symmetric
harmonic trap. Within the pseudopotential approximation, we solve the
Schroedinger equation exactly, discussing the limits of quasi-one and
quasi-two-dimensional geometries. Finally, we discuss the application of an
energy-dependent pseudopotential, which allows to extend the validity of our
results to the case of tight traps and large scattering lengths.Comment: RevTeX 4 pages, 2 figure
A bosonic Josephson junction controlled by a single trapped ion
We theoretically investigate the properties of a double-well bosonic
Josephson junction coupled to a single trapped ion. We find that the coupling
between the wells can be controlled by the internal state of the ion, which can
be used for studying mesoscopic entanglement between the two systems and to
measure their interaction with high precision. As a particular example we
consider a single Rb atom and a small Bose-Einstein condensate
controlled by a single Yb ion. We calculate inter-well coupling
rates reaching hundreds of Hz, while the state dependence amounts to tens of Hz
for plausible values of the currently unknown s-wave scattering length between
the atom and the ion. The analysis shows that it is possible to induce either
the self-trapping or the tunneling regime, depending on the internal state of
the ion. This enables the generation of large scale ion-atomic wavepacket
entanglement within current technology.Comment: 6 pages and 5 figures, including additional material. Accepted for
publication in Phys. Rev. Let
Laser cooling all the way down to molecular condensate
Numerical simulations show that laser cooling of fermions on the repulsive
side of the Feshbach resonance can sympathetically cool molecules well below
their condensation temperature.Comment: 7 pages, 2 .eps figure
Sympathetic cooling of trapped fermions by bosons in the presence of particle losses
We study the sympathetic cooling of a trapped Fermi gas interacting with an
ideal Bose gas below the critical temperature of the Bose-Einstein
condensation. We derive the quantum master equation, which describes the
dynamics of the fermionic component, and postulating the thermal distribution
for both gases we calculate analytically the rate at which fermions are cooled
by the bosonic atoms. The particle losses constitute an important source of
heating of the degenerate Fermi gas. We evaluate the rate of loss-induced
heating and derive analytical results for the final temperature of fermions,
which is limited in the presence of particle losses.Comment: 7 pages, 2 figures, EPL style; final versio
Laser cooling of a trapped two-component Fermi gas
The collective Raman cooling of a trapped two-component Fermi gas is
analyzed. We develop the quantum master equation that describes the collisions
and the laser cooling, in the festina lente regime, where the heating due to
photon reabsorption can be neglected. The numerical results based on Monte
Carlo simulations show, that three-dimensional temperatures of the order of
0.008 T_F can be achieved. We analyze the heating related to the background
losses, and conclude that our laser-cooling scheme can maintain the temperature
of the gas without significant additional losses. Finally we derive an analytic
expression for the temperature of a trapped Fermi gas heated by background
collisions, that agrees very well with the data obtained from the numerical
simulation.Comment: 5 pages, 3 figure
- …