One-Dimension Sub-Doppler Molasses in the Presence of Static Magnetic Field

Abstract

Sub-Doppler cooling has been achieved for the two closed hyperfine transitions: F = 4 → F' = 5 and F = 3 → F' = 2, of the cesium D2 line. One-dimension optical molasses is experimentally investigated and compared for both j → j + 1 and j → j - 1 transitions, on different laser polarization configurations, in the presence, and absence of a static magnetic field. One remarkable point is that cooling is obtained with blue laser detuning for the j → j - 1 transition. An applied static magnetic field can also shift the sub-Doppler-cooled molasses peaks to nonzero velocities without any extra heating, for the polarization gradient configurations.

A continuous beam of slow, cold cesium atoms magnetically extracted from a 2D magneto-optical trap

“…The low-velocity class is characterized by the measured drift coefficient of 2.2 mm s −1 mT −1 , significantly lower than the 2.98 mm s −1 mT −1 predicted [13] and measured [14] for a 1D σ + -σ − molasses in a longitudinal magnetic field (B k); the discrepancy would be even worse if one simply multiplied the predicted 1D drift velocity by √ 2 to account for our 2D, 45…”

Anisotropic magneto-optical trapping of atoms: capture efficiency and induced drift velocities

“…As shown in cells A5 and A6 of table 1, the experimental drift velocity (18-22 cm s −1 G −1 ) induced by a vertical magnetic field on an optical molasses or an anisotropic trap is significantly lower than the 29 √ 2 = 41 cm s −1 predicted by the 1D sub-Doppler model [19]. This discrepancy can be explained by the effect of additional laser beams which carry other polarization components than the σ + -σ − configuration of the 1D model.…”

Simplest atomic system for sub-Doppler laser cooling

“…For example, in circularly polarized light, optical pumping to the steady-state population distribution among the MF sublevels occurs before steady-state cooling on a cyclic transition begins. 3 Second, calculations of the damping force or the velocity distribution are simplified because of the relatively small Hamiltonian matrix. Third, Fe 0 requires that the ground state can be optically coupled to only one excited state so that ground-state coherences are not diluted by multiple excited states.…”