Next: Zooming in on the collision
Cooling is a three stage process. The first step is to use laser
cooling (1st stage) to lower the temperature from 300 K to about
100 microK. This technique uses scattering of near-resonant
photons to impart a slowing force on the atoms and hence reduce
their velocity. The atoms are then loaded into a magnetic trap,
where they are evaporatively (2nd stage) cooled by continuously
removing the high-energy tail of the thermal distribution of
energies (click
here
to learn more about evaporative cooling). The magnetic trap is
then converted into a double-well so it has two potential minima
(splitting the original cloud into two) and we prepare two nearly
identical clouds with a separation of 4 mm. The temperature for
each cloud is now about 10 microKelvin. The clouds are now further
evaporatively cooled (3rd stage) to a few hundred nanoKelvins.
Next: Zooming in on the collision
Up: What does it look like??
Previous: How do we detect the atoms??
nk
2004-11-02
