Interspecies singlet pairing in a mixture of two spin-1 Bose condensates.

We study the ground-state properties of a mixture formed by two spin-1 condensates in the absence of an external magnetic field. As the collisional symmetry between interspecies bosonic atoms is broken, the interspecies coupling interaction (β) and interspecies singlet-pairing interaction (γ) arise. The ground state can be calculated using the angular momentum theory analytically for γ=0. The full quantum approach of exact diagonalization is adopted numerically to consider the more general case as γ±0. We illustrate the competition between the two interspecies interactions and find that as singlet-pairing interaction dominates (or the total spin vanishes), there are still different types of singlet formations which are well determined by β. [ABSTRACT FROM AUTHOR]