Spectroscopic measurement of sub-Doppler cooling with two color σ+σ- laser configuration

雷士 松岡

Josh W. Dunn, Chris H. Greene

Nikita Kostylev, Eugene N. Ivanov, Michael Edmund Tobar +1 more

We report on the sub-Doppler laser cooling of neutral Yb171 and Yb173 in a magneto-optical trap (MOT) using the S10−P11 transition at 398.9 nm. We use two independent means to estimate the temperature of the atomic cloud for several of the Yb isotopes. The two methods of MOT cloud imaging and release-and-recapture show consistency with one another. Temperatures below 400 and 200 μK are recorded for Yb171 and Yb173, respectively, while ∼1 mK is measured for both Yb172 and Yb174. By comparison, the associated one-dimensional Doppler cooling temperature limit is 694 μK. The sub-Doppler cooling of the I=1/2Yb171 isotope in a σ+−σ− light-field trap adds further evidence that the Sisyphus cooling mechanism is occurring in such three-dimensional MOTs.

Jin 晋 Wei 魏, Di 迪 Wu 吴, T. V. Dong +3 more

Abstract We present a theoretical approach to achieve sub-Doppler cooling of magnesium fluoride (MgF) molecules by tuning the AC Stark shift with a blue-detuned laser. We study three blue-detuned magneto–optical trapping (MOT) schemes by using the Bayesian optimization method with the optical Bloch equations. We perform a comprehensive analysis of the relationship between the force in the MOT and the velocities and positions of the MgF molecules. Monte–Carlo simulations show that our MOT schemes can achieve a temperature as low as 28 μK and a density as high as 4.0 × 108 cm−3 at the conditions of a ratio of two laser intensities of 2:7, a detuning of 3Γ and a polarization configuration of σ −–σ +. These results provide a clear way for transferring a large number of MgF molecules into a conservative trap to enhance the subsequent cooling such as evaporative or sympathetic cooling.

Roger C. Brown, Saijun Wu, William D. Phillips +1 more

V. I. Balykin, Vladimir G. Minogin

We consider the propagation of an atomic beam in a quadrupole magnetic field under transverse irradiation by a cooling laser field. The cooling laser field was chosen in the form of a two-dimensional σ + -σ − configuration. We show that the sub-Doppler resonance in the radiation force can be used to reduce the diameter of the atomic beam to a value on the order of 10 mm. We establish that the simultaneous transverse cooling and compression of the atomic beam allow its phase density to be increased to values of the order of 10 −4 –10 −3 . The dipole interaction of an atom with the cooling and compressing laser field in a quadrupole magnetic field is analyzed in terms of a simple (3 + 5)-level model atom.