Experimental study of quantum chaos using atom optics technique

该项目旨在利用电磁操纵原子解决量子混沌问题。下面总结了我们为实现这一目标而进行的研究成果。1.我们预言，当磁场周期性调制时，囚禁在磁势中的原子的经典运动将变得混沌。Rb原子曾经被激光冷却到10 μ K，然后在录像带原子芯片上被参数加热。基于牛顿运动方程的数值模拟很好地再现了所观察到的光谱，表明原子的行为与经典粒子相似。我们用数值方法证明了原子云的冷却或加热，而不改变它们的内能。这些研究是与伦敦帝国理工学院冷物质中心合作进行的。空芯光纤中的原子在光波导中的横向运动在光强周期性调制时会出现混沌现象。对于入射原子的激光冷却，我们稳定了新引入的二极管激光器的频率。磁光阱的建造正在进行中。我们还开发了一种新的频率稳定方法，使用电磁感应的频率。两种类型的光学陷阱，这两种类型都使用对向传播的激光束，被开发用于微尺寸颗粒。首次展示了六角冰晶的激光捕获。在CO_2激光阱中，气流抵消了重力，缩短了阱时间.基于打靶法，提出了一种新的搜索不可积系统周期轨道的算法。用各向异性开普勒问题和电磁场中的氢原子验证了该方法的可行性。CPU时间大大节省。

The project aims to solve the problem of quantum chaos using electromagnetically manipulated atoms. Summarized below are the outcomes of our research carried out toward this goal.1. We predicted that classical motion of atoms trapped in a magnetic potential becomes chaotic when the magnetic field is periodically modulated. Rb atoms were once laser-cooled to 10 μ K, then parametrically heated on the video-tape atom chip. The observed spectrum is well reproduced by numerical simulations based on Newton's equations of motion, showing that atoms behave as classical particles. We numerically demonstrated cooling or heating of the atom cloud without changing their internal energy. These researches were carried out in cooperation with Center for Cold Matter, Imperial College London.2. The transverse motion of atoms optically guided in a hollow-core fiber becomes chaotic when the light intensity is periodically modulated. For laser-cooling of the incident atoms, we stabilized the frequency of the newly introduced diode laser. Construction of a magneto-optical trap is now in progress. We have also developed a novel method of frequency stabilization that uses electromagnetically induced transparency.3. Two types of optical traps, both of which use counter propagating laser beams, were developed for micro-sized particles. Laser trapping of hexagonal ice crystals was demonstrated for the first time. In the CO_2 laser trap, air flow counteracts gravity and prolongs the trap time.4. Based on the shooting method, we developed a novel algorithm to search periodic orbits of a non-integrable system. Its feasibility was tested on the anisotropic Kepler problem and a hydrogen atom in electromagnetic fields. CPU time was remarkably saved.