arXiv:cond-mat/0702649 · Physical Review A
Quantum dynamics of Raman-coupled Bose-Einstein condensates using Laguerre-Gaussian beams
Rina Kanamoto, Ewan M. Wright, Pierre Meystre
Abstract
We investigate the quantum dynamics of Raman-coupled Bose-Einstein condensates driven by laser beams that carry orbital angular momentum. By adiabatically eliminating the excited atomic state we obtain an effective two-state Hamiltonian for the coupled condensates, and quantization of the matter-wave fields results in collapse and revivals in the quantum dynamics. We show that the revival period depends on whether the initial nonrotating condensate displays broken $\mathrm{U}(1)$ symmetry or not, and that the difference may be detected by measuring the motion of quantized vortices that are nested in the density profile of the Raman-coupled condensates. We further study the steady-state population transfer using a linear sweep of the two-photon detuning, by which the atomic population is coherently transferred from an initial nonrotating state to the final vortex state.