玻色-爱因斯坦凝聚体穿越高斯光场的透镜效应

Lensing Effect Induced by a Bose-Einstein Condensate Passing a Gaussian Laser Field

在已有实验的基础上,从理论上研究了一维超冷玻色-爱因斯坦凝聚原子团横向穿越高斯型红(蓝)失谐光场后产生的位置超前(滞后)与聚焦(散焦)效应,重点考虑了加速度场、外加高斯光场与原子的偶极作用势和原子间s-波散射碰撞作用势,并分析比较了在这三种机制的相互竞争且共同作用下,探测原子波包的位置和高度变化。加速度场仅影响波包位置,并不引起形变,原子间的强相互吸引作用可导致波包剧烈形变,甚至崩塌,而排斥作用会加快波包扩散。数值模拟结果与文献实验结果在红失谐光场下十分吻合;通过数值模拟还得到了蓝失谐光场下的理论预测结果。研究结果为今后实验研究光与原子相干操控提供了可行性方案。

On the basis of recent experiment, the focusing and leading effect of an ultra-cold Bose-Einstein condensate （BEC） is theoretically investigated when it transversely passes through a red-detuned Gaussian field. Particular attentions are paid on the focusing （or defocusing） in shape and leading （or lagging） in position of the atoms, which are induced by a red-detuned （or blue-detuned） laser field. The time-dependent motion of BEC atoms and its final status are presented under the influences of the acceleration, the dipolar interaction between atom and optical field, as well as the s-wave scattering collisions of individual atoms. In addition, the acceleration only influences position of the atoms; an attractive or repulsive s-wave interaction can bring on a strong deformation to the atoms, making them collapse or diffusion in essence. Compared to the previous experiments, the findings are well consistent in the regime of a red-detuned laser field, moreover, an extension to the blue-detuned field is predicted. The results may provide more feasible ways for studying coherent atom-light manipulations in the field of ultra-cold atoms and molecules in the future.