Xiong Dezhi, Wang Pengjun, Fu Zhengkun, Zhang Jing
State Key Laboratory of Quantum Optics and Quantum Optics Devices, Institute of Opto-Electronics, Shanxi University, Taiyuan, P.R.China.
Opt Express. 2010 Jan 18;18(2):1649-56. doi: 10.1364/OE.18.001649.
We have studied the locomotion track of (87)Rb Bose-Einstein condensate during decompressing the trap into the center of the glass cell in a quadrupole-Ioffe configuration trap. In order to change the position of the BEC, the current in the quadrupole coils is reduced while the current in the Ioffe coil keeps constant. Because of the strongly reduced trap frequencies of the moved trap, the BEC considerably sags down due to the gravity. Thus an inflexion point exists in the process of moving BEC. When rubidium atoms go over the inflexion point, they cannot keep in balance under the gravity and the force provided by a magnetic field, and flow downward and towards Ioffe coil. By utilizing this effect, the trapped atoms with the spin state |F = 2,mF = 1>, which are left over in the BEC, can be separated from the BEC of |F = 2,mF = 2> state.
我们研究了在四极-伊夫（quadrupole-Ioffe）构型阱中将阱解压缩到玻璃细胞中心过程中（87）Rb玻色-爱因斯坦凝聚体的运动轨迹。为了改变玻色-爱因斯坦凝聚体（BEC）的位置，四极线圈中的电流减小，而伊夫线圈中的电流保持恒定。由于移动阱的阱频率大幅降低，玻色-爱因斯坦凝聚体因重力而大幅下垂。因此，在移动玻色-爱因斯坦凝聚体的过程中存在一个拐点。当铷原子越过拐点时，它们在重力和磁场提供的力作用下无法保持平衡，从而向下流动并流向伊夫线圈。利用这种效应，可以将玻色-爱因斯坦凝聚体中剩余的处于自旋态|F = 2，mF = 1>的捕获原子与|F = 2，mF = 2>态的玻色-爱因斯坦凝聚体分离。
