Spin-polarized atoms in a circularly polarized optical dipole trap

The behavior of atoms in an optical far-off resonance trap is found to depe nd strongly on the trap polarization. Large loss rates occur unless the pol arization is perfectly linear or perfectly circular, in which case exponent ial lifetimes up to 10 s are observed. Through optimization of trap loading , samples of 4 x 10(6) atoms are obtained in a circularly polarized trap. S pin polarization of 98(1)% is measured. This trap should prove useful for p recision measurements such as beta-decay asymmetry and should make rf cooli ng possible in optical traps.