Gravitational and collective effects in an output coupler for a Bose-Einstein condensate in an atomic trap

A three-component vector quantum field theory is developed to describe the electronic-spin-resonance interaction of a magnetically trapped Bose-Einstein condensate with a radio frequency field. The theory is directly applied to simulate the recent experiment of Mewes et nl. for an output coupler for a Bose-Einstein condensate in a magnetic trap [Phys. Rev. Lett. 78, 582 (1997)]. By employing the mean-field approach, we study the collective dynamics of the multicomponent matter field via the nonlinear Schrodinger equation. Including the effect of gravity, we study the spin-resonance Rabi oscillations for the three-component Bose-Einstein condensate in three ground-state hyperfine levels and simulate the dynamic expansion of the condensate components coupled nut of the magnetic trap. [S1050-2947(98)00602-7].