Atom-chip Bose-Einstein condensation in a portable vacuum cell

DU et al. PHYSICAL REVIEW A 70, 053606 (2004)
which to desorb rubidium. Pyrex was chosen because prior
LIAD experiments [13–15] were successfully performed using
Pyrex. The helix shape, made in-house, was chosen arbitarily.
Probably any shape that increases the surface area
for desorption will suffice. In the hopes of eliminating the
bulky uv lamps, we attempted LIAD using blue LED’s as
well as laser light at =532 nm 100 mW and 408 nm
10 mW. None were as effective as the incandescent lamps
(150 W total). We were able to capture rubidium atoms even
with the LED’s, suggesting the possibility of a more efficient
and compact LIAD source.
The achievement of BEC demonstrates the viability of
small and portable chip-based vacuum cells for atom chip
applications. Our results suggest that a BEC suitable vacuum
cell can be made substantially smaller still. In particular, all
of the key elements except for the ion pump reside within the
glass-to-metal transition region, as shown in Fig. 1(b). The
8 L/s ion pump is in fact already limited by the cell structure
itself to a pumping speed of about 2 1 L/s. Thus, we expect
it is possible to reduce the total volume of the vacuum system
to well less than 0.5 L, dominated by a small ion pump.
As the cell itself becomes smaller, many of the practical
parameters also improve, such as the size and power requirements
of the magnetic coils. On the other hand, the MOT
capture volume is small, resulting in a small MOT and subsequent
small BEC. It should be noted that a small BEC does
not prohibit its utility [16,17].
In summary, we have successfully demonstrated Bose-
Einstein condensation in a compact and portable vacuum
system. The size reduction and simplification are largely due
to the techniques that allow all cooling steps to take place in
a single small chamber and the chip-based electrical
feedthroughs, which greatly facilitate chip connections. In
our experiments, we have succeeded in realizing a “plug-in”
concept where the atom chip vacuum cell is plugged into an
existing optical and electronic system. Through this concept,
we hope that atom chip development and experiments can
proceed more rapidly.
The authors thank E. A. Cornell, D. Jin, Y. J. Wang, T.
Kishimoto, S. Inoyoe, and J. Goldwin for helpful discussions.
This work was supported in part by ARO and the
Office of the Secretary of Defense through a MURI program
in Ultracold Atom Optics Science and Technology (Grant
No. DAAD19-00-1-0163); this work was also made possible
by funding from the Office of Naval Research (Grant No.
N00014-03-1-0551) and the National Science Foundation
(Grant No. PHY-0096822). M.B.S. gratefully acknowledges
support from the NSF-IGERT program. D.Z.A. gratefully acknowledges
support of the Alexander von Humboldt Foundation.
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