旋量凝聚体中偶极作用的平均场效应

The Mean Field Effects of Dipolar Interaction on the Spinor Condensates

为了揭示偶极相互作用对于冷原子体系磁学性质的影响,研究了偶极自旋-1,自旋-2和混合自旋-1玻色-爱因斯坦凝聚体(BEC)的基态性质.首先用平均场方法处理场算符并作单模近似,然后对能量泛函最小化,便得到系统的基态相图,再与无偶极作用的旋量BEC相图比较.计算结果表明,在偶极相互作用下,自旋-1系统中铁磁相的简并被解除,自旋-2和混合自旋-1系统中铁磁相与其它相的边界发生移动.偶极相互作用对于自旋-2碱金属原子的影响在量值上小于对自旋-1碱金属原子的影响,在形式上类似于对于混合自旋-1BEC的影响.各相边界的计算量值可为实验观察提供参考.

In order to uncover the effects of dipolar interaction on the magnetic properties of cold atom system,the ground state properties of dipolar spin-1,spin-2and binary mixed spin-1Bose-Einstein condensates（BEC）were studied.By treating field operator with mean field method and single model approximation,and minimizing the energy functional,the ground state phase diagrams were got.Then the diagrams with and without dipolar interaction were compared.The calculations show that under the dipole interaction,the degeneracy for ferromagnetic phases of spinor BEC is released and the boundaries between ferromagnetic and other phases are moved.The influence of dipole interaction on the spin-2alkali atoms is smaller than for spin-1alkali atoms in quantity and is analogous with binary mixed spin-1BEC qualitatively.The calculated quantities for every phase boundary provide reference for the related experiments.