量子模型分析激光驻波原子透镜的像差

采用量子模型对近共振激光驻波原子透镜会聚Cr原子束、形成纳米量级光栅结构的物理过程进行数值模拟。为提高原子透镜的成像质量,对各种像差,如衍射像差、球差、色差、及原子束发散角、原子磁支能级、原子同位素等因素引起的像差进行了理论分析。模拟结果表明,相比粒子光学模型,量子模型能更加精确地描述原子会聚结果,且能解释原子在驻波光场中的衍射现象。在各种像差中,原子束发散角是最主要的因素,其影响大于衍射像差、球差、色差。原子的磁支能级、同位素等因素对像差影响很小,可以忽略不计。激光冷却准直原子束的方法可以减小束发散角引起的像差,压缩原子速度Vz分布范围的方法可以减小色差。

Quantum Mechanical Analysis of Aberration in Cr Atom Lens Generated by a Laser Standing Wave

A grating nanostructure generated by focusing Cr atoms with nearly resonant laser standing wave(SW)atom lens was numerically simulated using the quantum-mechanical model.To improve the imaging quality of atom lens,theoretical analysis was performed to describe the aberration of atom lens,including diffractive aberration,spherical aberration,chromatic aberration,the aberration caused by atom beam divergence angle,by magnetic sublevel structure and by isotopes.It was shown that quantum approach is more precise to describe atom focusing compared with particle-optics approach.The diffraction of atoms in laser standing wave(SW)field was explained with quantum approach.It was also shown in simulation results that aberration originates mainly from beam divergence,which is much larger than the diffractive aberration,the spherical aberration and the chromatic aberration.The aberration caused by magnetic sublevel structure and isotopes are small enough to be neglected.It is a useful method of collimating atomic beams with laser cooling to decrease the aberration caused by beam divergence.Chromatic aberration can be decreased by narrowing the statistical distribution of atomic velocity Vz.