title: Cooling Bose-Einstein condensates below 500 picokelvin.
abstract: Spin-polarized gaseous Bose-Einstein condensates were confined by a combination of gravitational and magnetic forces. The partially condensed atomic vapors were adiabatically decompressed by weakening the gravito-magnetic trap to a mean frequency of 1hertz, then evaporatively reduced in size to 2500 atoms. This lowered the peak condensate density to 5 x 10(10) atoms per cubic centimeter and cooled the entire cloud in all three dimensions to a kinetic temperature of 450 +/- 80 picokelvin. Such spin-polarized, dilute, and ultracold gases are important for spectroscopy, metrology, and atom optics.
authors.affiliation: Department of Physics, MIT-Harvard Center for Ultracold Atoms, and Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, MA 02139, USA. ael@mit.edu
authors.forename: A E
authors.initials: AE
authors.lastname: Leanhardt
authors.forename: T A
authors.initials: TA
authors.lastname: Pasquini
authors.forename: M
authors.initials: M
authors.lastname: Saba
authors.forename: A
authors.initials: A
authors.lastname: Schirotzek
authors.forename: Y
authors.initials: Y
authors.lastname: Shin
authors.forename: D
authors.initials: D
authors.lastname: Kielpinski
authors.forename: D E
authors.initials: DE
authors.lastname: Pritchard
authors.forename: W
authors.initials: W
authors.lastname: Ketterle