10 research outputs found
Laser cooling of a magnetically guided ultra cold atom beam
We report on the transverse laser cooling of a magnetically guided beam of
ultra cold chromium atoms. Radial compression by a tapering of the guide is
employed to adiabatically heat the beam. Inside the tapered section heat is
extracted from the atom beam by a two-dimensional optical molasses
perpendicular to it, resulting in a significant increase of atomic phase space
density. A magnetic offset field is applied to prevent optical pumping to
untrapped states. Our results demonstrate that by a suitable choice of the
magnetic offset field, the cooling beam intensity and detuning, atom losses and
longitudinal heating can be avoided. Final temperatures below 65 microkelvin
have been achieved, corresponding to an increase of phase space density in the
guided beam by more than a factor of 30.Comment: 9 pages, 4 figure
Continuous atom laser with Bose-Einstein condensates involving three-body interactions
We demonstrate, through numerical simulations, the emission of a coherent
continuous matter wave of constant amplitude from a Bose-Einstein Condensate in
a shallow optical dipole trap. The process is achieved by spatial control of
the variations of the scattering length along the trapping axis, including
elastic three body interactions due to dipole interactions. In our approach,
the outcoupling mechanism are atomic interactions and thus, the trap remains
unaltered. We calculate analytically the parameters for the experimental
implementation of this CW atom laser.Comment: 11 pages, 4 figure
A proposal for continuous loading of an optical dipole trap with magnetically guided ultra cold atoms
The capture of a moving atom by a non-dissipative trap, such as an optical
dipole trap, requires the removal of the excessive kinetic energy of the atom.
In this article we develop a mechanism to harvest ultra cold atoms from a
guided atom beam into an optical dipole trap by removing their directed kinetic
energy. We propose a continuous loading scheme where this is accomplished via
deceleration by a magnetic potential barrier followed by optical pumping to the
energetically lowest Zeeman sublevel. We theoretically investigate the
application of this scheme to the transfer of ultra cold chromium atoms from a
magnetically guided atom beam into a deep optical dipole trap. We discuss the
realization of a suitable magnetic field configuration. Based on numerical
simulations of the loading process we analyze the feasibility and efficiency of
our loading scheme.Comment: 10 pages, 5 figure
A slow gravity compensated Atom Laser
We report on a slow guided atom laser beam outcoupled from a Bose-Einstein
condensate of 87Rb atoms in a hybrid trap. The acceleration of the atom laser
beam can be controlled by compensating the gravitational acceleration and we
reach residual accelerations as low as 0.0027 g. The outcoupling mechanism
allows for the production of a constant flux of 4.5x10^6 atoms per second and
due to transverse guiding we obtain an upper limit for the mean beam width of
4.6 \mu\m. The transverse velocity spread is only 0.2 mm/s and thus an upper
limit for the beam quality parameter is M^2=2.5. We demonstrate the potential
of the long interrogation times available with this atom laser beam by
measuring the trap frequency in a single measurement. The small beam width
together with the long evolution and interrogation time makes this atom laser
beam a promising tool for continuous interferometric measurements.Comment: 7 pages, 8 figures, to be published in Applied Physics