中性原子的表面双磁光阱及其应用

提出了一种新的采用载流导线的表面双磁光阱(MOT)方案(即双U型导线磁光阱方案)。通过改变中间U型导线中的电流大小,即可将一个双磁阱连续地合并为一个单磁阱,反之亦然。详细计算和分析了上述双U型载流导线磁光阱方案的磁场及其梯度的空间分布,研究发现当导线中的电流为600 A,z方向均匀偏置磁感应强度为-4.0×10-3 T时,双U型导线方案产生的两个磁阱中心的磁场梯度约为1.5×10-3~2.5×10-3 T/cm,结合通常制备磁光阱时所用的三维粘胶(Molasses)光束即可在基底表面附近形成一双磁光阱。理论分析表明在弱光近似下,每个磁光阱中所能俘获的85Rb原子数约为106 量级,相应的磁光阱温度约为270μK。由于双磁光阱可以独立制备,所以双U型导线方案特别适用于制备双样品磁光阱,并用于研究双原子样品的冷碰撞性质。

Double-Well Surface Magneto-Optical Trap for Neutral Atoms and Its Potential Applications

A novel scheme is proposed to form double-well magneto-optical surface trap for cold atoms using double U-shaped current-carrying wires. It shows that the double-well magnetic trap proposed here could be continuously transfered into a single one by adjusting the current in an inner U-shaped wire from a suitable value to zero, and vice versa. The spatial distributions of magnetic fields from double U-shaped current-carrying wires layout and their gradients are calculated and analyzed. It is found that the magnetic field gradient near the center of each magnetic trap generated by the double U-shaped wires is about 1.5×10-3～2.5 ×10-3T/cm when the currents in the double U-shaped wires are both equal to 600 A and the inhomogeneous bias magnetic field in z-direction is -4.0 ×10-3T. By associating with 3D optical Molasses beams used in the usual magneto-optical trap (MOT), the double-well magneto-optical surface trap can be used to realize double-well MOT near the surface of wire plane. Under the approximation of low intensity, a cold atomic sample with a captured number of ～106 atoms at a temperature of about 270 μK can be obtained in each 85Rb atomic MOT. Since each MOT in two-species MOT can be prepared independently, the controllable double-well trap can be used to study the cold collisions between two different atomic samples.