Realization and characterization of a continuous-wave atom laser

我们建立了一个由Rb原子组成的塞曼慢化器，它产生速度约为20m/S的慢原子束，我们用这个慢原子束加载磁光陷阱，得到了大量的冷原子样品(约10^10)。然后我们用一个反亥姆霍兹线圈产生的四极磁场来捕获这个原子样品。更重要的是。在另一个具有不同陷阱中心的反亥姆霍兹线圈的帮助下，我们将原子样品绝热地移动到玻璃表面附近。当较热的原子选择性地与表面碰撞时，蒸发冷却起作用，相空间密度增加了2倍。为了证明相空间密度有更大的提高，我们尝试将四极磁场中的原子样品转移到由Z形导线产生的Ioffe-Pritchard磁场中，并对原子样品进行绝热压缩。然而，转移效率只有10%，因此我们不能达到足够高的密度来进行蒸发冷却，在未来，我们希望将在MOT中捕获的原子直接转移到Ioffe-Pritchard磁阱中，绝热压缩，并在草表面附近进行蒸发冷却。我们发表了一篇关于产生高强度超冷原子束技术的论文(Rev.Sci)。Instrum。77,023106(2006年))，这是与麻省理工学院合作研究的结果。

We have constructed a Zeeman slower of rubidium atoms which produces a slow atomic beam with a velocity of about 20 m/s. We loaded a magneto-optical trap with this slow atomic beam, resulting in a large number of cold atomic sample (about 10^10. We then trap this atomic sample with a quadrupole magnetic field which was produced by an anti-Helmholtz coil. Furthermore. With the help of another anti-Helmholtz coil, which has a different trap center, we shifted the atomic sample close to the glass surface adiabatically. As the hotter atoms selectively collide with the surface, evaporative cooling works, and the phase space density was increased by a factor of 2. To demonstrate a much larger enhancement in the phase space density, we tried to transfer the atomic sample in a quadrupole magnetic field to an Ioffe-Pritchard magnetic field which is produced by a Z-shaped wire, and adiabatically compress the atomic sample. However, the transfer efficiency was as low as 10 %, therefore we could not achieve a density high enough to perform evaporative cooling, In the future, we want to transfer the atom, captured in a MOT directly to an Ioffe-Pritchard magnetic trap, adiabatically compress, and perform evaporative cooling near the grass surface. We published a paper on the techniques of producing a high-intensity ultra-cold atomic beam (Rev. Sci. Instrum. 77, 023106(2006)) as a result of a cooperative research with MIT.