Laser deceleration and trapping of metastable helium atoms

Abstract

Metastable helium atoms with an initial velocity of 1000 m/s are decelerated using the Zeeman slowing method. A magneto-optical trap operating in a novel regime with large laser detuning ( δ = −25 Γ) is loaded with 3 × 10 7 atoms at a temperature of 2 mK. The volume of trapped atoms is large (∼ 0.1 cm 3) and atoms predominantly interact with light at the edges of the trapping volume. This situation is favourable to minimise trap losses by light-induced Penning ionisation. The trap lifetime is 0.8 s. The number of trapped atoms is more than two orders of magnitude larger than previously obtained for metastable helium. The feasibility to use this trap as a first stage to reach the Bose-Einstein-Condensation regime is discussed.