Raman sideband cooling of rubidium atoms in optical lattice**Project supported by the National Natural Science Foundation of China (Grant No. 51275523), the Specialized Research Fund for the Doctoral Program of Higher Education of China (Grant No. 20134307110009), the Graduate Innovative Research Fund of Hunan Province, China (Grant No. CX20158015), and the Excellent Graduate Innovative Fund of National University of Defense

Abstract

We develop a simple and practical scheme to apply sideband cooling to a cloud of rubidium atoms. A sample containing 4 × 10 Rb is trapped in a far red detuned optical lattice. Through optimizing the relevant parameters, i.e., laser detuning, magnetic field, polarization, and duration time, a temperature around 1.5 μK and phase space density close to 1/500 are achieved. Compared with polarization gradient cooling, the temperature decreases by around one order of magnitude. This technique could be used in high precision measurement such as atomic clocks and atom interferometer. It could also serve as a precooling means before evaporation cooling in a dipole trap, and may be a promising method of achieving quantum degeneracy with purely optical means.