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.

Conditions for one-dimensional supersonic flow of quantum gases

“…These condensates are weakly interacting quantum gases, not primarily quantum liquids, resembling very closely the perfect Bogoliubov gas. The alkali condensates are the coldest quantum gases currently available [15]. The condensates also allow many ways of experimental manipulation.…”

Spin Gradient Demagnetization Cooling of Ultracold Atoms

“…est temperature ever measured in an equilibrated kinetic system [29], and it is within a factor of 2 of the expected magnetic ordering temperature [5].…”

Time-orbiting potential trap for Bose-Einstein condensate interferometry

“…We estimate the temperature of this cloud to be 850 pK. Although lower temperatures have been observed in Na [16], this is the lowest temperature achieved for Rb atoms of which we are aware.…”

“…Weak three-dimensional confinement has previously been observed [16], but in this paper we present a novel weakly confining waveguide that is particularly well-suited for the demands of atom interferometry.…”