High-brightness atom source for atomic fountains

Laser collimation of a continuous beam of cold atoms using Zeeman-shift degenerate-Raman-sideband cooling

“…We operate sideband cooling in continuous mode on an atomic beam. The initial temperature as given by our continuous cold atom source ͑60 K͒ is much higher than that of sequential experiments ͑2-3 K͒ [12,15,16]. The lattice potential depth seen by the atoms when crossing the collimation zone is not constant (because of Gaussian laser beams).…”

“…In comparison with previous work [12,15,16] our experiment has the following distinctive features. We operate sideband cooling in continuous mode on an atomic beam.…”

“…Later, following a theoretical proposal by Taïeb et al [11], it was adapted to neutral atoms in optical lattices by several groups [12][13][14]. Recently, the group of Chu developed a particularly efficient scheme [15] for three-dimensional (3D) cooling of a pulsed cesium beam [16]. Here we report on a demonstration of this mechanism for two-dimensional cooling of a continuous atomic beam.…”

“…The cooling scheme we use is similar to that proposed by Chu and co-workers [15,16]. Let us briefly recall its principle.…”

“…Due to the Gaussian shape of laser beams, atoms should undergo an adiabatic expansion while leaving the cooling zone and this should reduce the temperature [15][16][17]. To check if this adiabatic cooling takes place in our experiment we have masked the upper part (approximately 25%) of the laser beams and we made the following observations.…”