Regular and irregular spin-mixing dynamics in coupled spin-1 atomic and molecular Bose-Einstein condensates

Regular and irregular spin-mixing dynamics are studied in a spin-1 atomic Bose-Einstein condensate coupled with a molecular condensate. Based on the experimental photoassociation spectroscopy of Rb-87 spin-1 atoms, a two-channel model is proposed, in which two zero-spin atoms can be associated with a molecular state via a laser field, and a pair of +1- and -1-spin atoms can also be associated with the same molecular state via the same laser field. We find that the spin-mixing dynamics can be manipulated by the laser field and a magnetic field. Both regular and irregular oscillations can be observed under different parameters. Using the Fourier transform analysis, the spin-mixing dynamics may be changed from the regular oscillation with localized spectral distributions to irregular oscillation with a broad spectral distribution.