弱磁场下三阱光学超晶格中自旋为1的超冷原子特性研究

Ultracold spin-1 atoms in three-well optical superlattice under a weak magnetic field

双阱光学超晶格中的超冷原子是近期冷原子物理领域的研究热点.本文推广提出了实现三阱光学超晶格的方案,并采用精确对角化的方法分别研究了弱磁场下对称三阱光学超晶格中铁磁性和反铁磁性的自旋为1的原子系统的基态,发现二者的相图很不相同:反铁磁性原子对应的相图中没有沿磁场方向总自旋磁量子数为±2的基态,而铁磁性原子对应的相图中可能有.在负的二次塞曼能量区域,铁磁性原子的相图中只有完全极化态.分析了可控参数影响基态的物理本质.由于这些量子自旋态可以通过调节外磁场和光势垒的高度非常简便而精确地控制,适合用来研究自旋纠缠.

Ultracold atoms trapped in an optical lattice of double-well potential, the so-called optical superlattice, have received much attention in the field of cold atoms. A protocol generalized to three-well optical superlattice is suggested in this paper. The ground- state diagrams of ultracold spin-1 atoms trapped in a symmetric three-well optical superlattice in a weak magnetic field are studied based on the exact diagonalization. It is shown that the ground-state diagrams are remarkably different for the ferromagnetic and antiferromagnetic atoms. There does not exist the type of ground state for the antiferromagnetic interaction atoms, where the magnetic quantum number of the total spin of the system along the external magnetic field are ~2. But for the ferromagnetic interaction atoms, there do exist. In addition, there exist only the fully polarized ground-states for the ferromagnetic atoms in the negative quadratic- Zeeman-energy region. The physicsal origin of the dependence of the ground states on the controllable parameters are analyzed. These quantum spin-states can be controlled easily and exactly by modulating the external magnetic field and the height of the optical barrier, which may be a tool for the study of spin-entanglement.