Three Dimensional Raman Cooling using Velocity Selective Rapid Adiabatic Passage

Axel Kuhn (1) , Hélène Perrin (1) , Wolfgang Hänsel (1) , Christophe Salomon (1)

1 LKB (Lhomond) - Laboratoire Kastler Brossel

We present a new and efficient implementation of Raman cooling of trapped atoms. It uses Raman pulses with an appropriate frequency chirp to realize a velocity selective excitation through a rapid adiabatic passage. This method allows to address in a single pulse a large number of non zero atomic velocity classes and it produces a nearly unity transfer efficiency. We demonstrate this cooling method using cesium atoms in a far-detuned crossed dipole trap. Three-dimensional cooling of $1 \times 10^{5}$ atoms down to $2~\mu$K is performed in 100~ms. In this preliminary experiment the final atomic density is $1.3\times 10^{12}$~at/cm$^3$ (within a factor of 2) and the phase-space density increase over the uncooled sample is 20. Numerical simulations indicate that temperatures below the single photon recoil temperature should be achievable with this method.

Mots clés: Trapped atoms; Laser cooling; Ultracold atoms; Coherent optical effects

Domaines: Gaz Quantiques [cond-mat.quant-gas]; Physique Quantique [quant-ph]; Physique Atomique [physics.atom-ph]

Axel Kuhn, Hélène Perrin, Wolfgang Hänsel, Christophe Salomon. Three Dimensional Raman Cooling using Velocity Selective Rapid Adiabatic Passage. OSA TOPS on Ultracold Atoms and BEC, 1997, 7, pp.58. ⟨hal-00626010v2⟩