Neutral Cesium Atoms in Strong Magnetic-Quadrupole Fields at Sub-Doppler Temperatures

Abstract

We have investigated optical capture of neutral cesium atoms by radiation pressure forces in a stiff magnetic-quadrupole field. Permanent magnets were used to generate field gradients ranging from 60 G/cm to more than 300 G/cm. With increasing gradient we observe a step decrease in the equilibrium number of trapped atoms but only a moderate reduction of their density. From the dynamics of the trapped atomic sample we derive temperatures as low as 40 μK or 30% of the Doppler limit even in these strong magnetic-quadrupole fields.