REPORT OF SCIENCE
AT WILLIAMS COLLEGE
2002 – 2003
A
300 µK cloud of rubidium-87 atoms held in a magneto-optical
trap.
Cover
The cover is a photograph of a trapped cloud
of extremely cold rubidium atoms taken in the lab of Professor Dwight Whitaker.
Using carefully tuned diode lasers and magnetic fields, atoms can be trapped
and cooled to near absolute zero. The glowing cloud in the image is nearly
one billion rubidium atoms held in a vacuum chamber at a temperature of approximately
300 µK. The reddish glow of the cloud is light scattered from the lasers
used to trap the atoms. This magneto-optical trap (MOT) represents the first
stage in the cooling process needed to form a new state of matter called a
Bose-Einstein condensate (BEC). After the atoms are collected in the MOT they
are transferred to another laser trap where they are cooled to below one-millionth
of a degree above absolute zero. At these extremely low temperatures, the
atoms undergo a phase transition to form a BEC. Once in this phase the atoms
cease to behave as a collection of individual atoms, but instead act as one
“super-atom”. Studies of the BEC phase transition should help
us gain insight into the fundamentals of quantum phase transitions and lead
to a better understanding of the phenomena of superfluidity and superconductivity.
Credits
The Science Executive Committee wishes to express its gratitude to the extensive
efforts of all the science departmental executive assistants in preparing contributions
for this publication, and to Kate Fletcher for assembling this material in its
final form.
Editor: Dr. Bryce Babcock
