High-field trap to Bose condense caesium

All attempts, to date, to Bose condense caesium have been thwarted by the unexpectedly high two-body, inelastic spin-flip cross section. In this paper we discuss, quantitatively, a hybrid laser/magnetic trap that overcomes this problem by trapping the true hyperfine ground state at a magnetic field maximum. The trap is toroidal and the atoms are trapped in a thin annulus. The geometry may well be ideal for studies of quantized circulation and for the investigation of persistent currents in Bose-Einstein condensates.