66 research outputs found
Bose-Einstein Condensation in a Surface Micro Trap
Bose-Einstein condensation has been achieved in a magnetic surface micro trap
with 4x10^5 87Rb atoms. The strongly anisotropic trapping potential is
generated by a microstructure which consists of microfabricated linear copper
conductors at a width ranging from 3 to 30 micrometer. After loading a high
number of atoms from a pulsed thermal source directly into a magneto-optical
trap (MOT) the magnetically stored atoms are transferred into the micro trap by
adiabatic transformation of the trapping potential. The complete in vacuo trap
design is compatible with ultrahigh vacuum below 2x10^(-11) mbar.Comment: 4 pages, 4 figure
Microelectromagnets for Trapping and Manipulating Ultracold Atomic Quantum Gases
We describe the production and characterization of microelectromagnets made
for trapping and manipulating atomic ensembles. The devices consist of 7
fabricated parallel copper conductors 3 micrometer thick, 25mm long, with
widths ranging from 3 to 30 micrometer, and are produced by electroplating a
sapphire substrate. Maximum current densities in the wires up to 6.5 * 10^6 A /
cm^2 are achieved in continuous mode operation. The device operates
successfully at a base pressure of 10^-11 mbar. The microstructures permit the
realization of a variety of magnetic field configurations, and hence provide
enormous flexibility for controlling the motion and the shape of Bose-Einstein
condensates.Comment: 4 pages, 3 figure
Combined chips for atom-optics
We present experiments with Bose-Einstein condensates on a combined atom
chip. The combined structure consists of a large-scale "carrier chip" and
smaller "atom-optics chips", containing micron-sized elements. This allows us
to work with condensates very close to chip surfaces without suffering from
fragmentation or losses due to thermally driven spin flips. Precise
three-dimensional positioning and transport with constant trap frequencies are
described. Bose-Einstein condensates were manipulated with submicron accuracy
above atom-optics chips. As an application of atom chips, a direction sensitive
magnetic field microscope is demonstrated.Comment: 9 pages, 9 figure
Bose-Einstein Condensates in Magnetic Waveguides
In this article, we describe an experimental system for generating
Bose-Einstein condensates and controlling the shape and motion of the
condensate by using miniaturised magnetic potentials. In particular, we
describe the magnetic trap setup, the vacuum system, the use of dispenser
sources for loading a high number of atoms into the magneto-optical trap, the
magnetic transfer of atoms into the microtrap, and the experimental cycle for
generating Bose-Einstein condensates. We present first results on outcoupling
of condensates into a magnetic waveguide and discuss influences of the trap
surface on the ultracold ensembles.Comment: 8 pages, 9 figure
A fundamental limit for integrated atom optics with Bose-Einstein condensates
The dynamical response of an atomic Bose-Einstein condensate manipulated by
an integrated atom optics device such as a microtrap or a microfabricated
waveguide is studied. We show that when the miniaturization of the device
enforces a sufficiently high condensate density, three-body interactions lead
to a spatial modulational instability that results in a fundamental limit on
the coherent manipulation of Bose-Einstein condensates.Comment: 6 pages, 3 figure
A waveguide atom beamsplitter for laser-cooled neutral atoms
A laser-cooled neutral-atom beam from a low-velocity intense source is split
into two beams while guided by a magnetic-field potential. We generate our
multimode-beamsplitter potential with two current-carrying wires on a glass
substrate combined with an external transverse bias field. The atoms bend
around several curves over a -cm distance. A maximum integrated flux of
is achieved with a current density of
in the 100- diameter
wires. The initial beam can be split into two beams with a 50/50 splitting
ratio
An optical lattice on an atom chip
Optical dipole traps and atom chips are two very powerful tools for the
quantum manipulation of neutral atoms. We demonstrate that both methods can be
combined by creating an optical lattice potential on an atom chip. A
red-detuned laser beam is retro-reflected using the atom chip surface as a
high-quality mirror, generating a vertical array of purely optical oblate
traps. We load thermal atoms from the chip into the lattice and observe cooling
into the two-dimensional regime where the thermal energy is smaller than a
quantum of transverse excitation. Using a chip-generated Bose-Einstein
condensate, we demonstrate coherent Bloch oscillations in the lattice.Comment: 3 pages, 2 figure
Reduction of Magnetic Noise in Atom Chips by Material Optimization
We discuss the contribution of the material type in metal wires to the
electromagnetic fluctuations in magnetic microtraps close to the surface of an
atom chip. We show that significant reduction of the magnetic noise can be
achieved by replacing the pure noble metal wires with their dilute alloys. The
alloy composition provides an additional degree of freedom which enables a
controlled reduction of both magnetic noise and resistivity if the atom chip is
cooled. In addition, we provide a careful re-analysis of the magnetically
induced trap loss observed by Yu-Ju Lin et al. [Phys. Rev. Lett. 92, 050404
(2004)] and find good agreement with an improved theory.Comment: 25 pages with 9 figures ep
Loading of a Rb magneto-optic trap from a getter source
We study the properties of a Rb magneto-optic trap loaded from a commercial
getter source which provides a large flux of atoms for the trap along with the
capability of rapid turn-off necessary for obtaining long trap lifetimes. We
have studied the trap loading at two different values of background pressure to
determine the cross-section for Rb--N collisions to be 3.5(4)x10^{-14} cm^2
and that for Rb--Rb collisions to be of order 3x10^{-13} cm^2. At a background
pressure of 1.3x10^{-9} torr, we load more than 10^8 atoms into the trap with a
time constant of 3.3 s. The 1/e lifetime of trapped atoms is 13 s limited only
by background collisions.Comment: 5 pages, 5 figure
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