Coherent and Optimal Control of Ultracold Atoms and Molecules: Applications and Methodological Developments

超冷热和量子简并气体作为真正的量子对象代表了量子控制的理想候选者。利用量子干涉的相干控制技术目前才被引入到这一领域。在这个项目中，将从理论上研究用短的、形状的激光脉冲主动控制超冷系统的可能性。将采用相干控制方案和最优控制理论。来自超冷原子的分子的结合将作为第一个例子来测试流行的相干控制策略，如泵倾倒方案和受激拉曼绝热通道。重点将放在分子相互作用的现实处理上，以便与正在进行的实验进行比较。将研究振动冷却的策略，并探索在光学晶格中使用形状激光脉冲进行超冷原子的量子计算。该项目的第二部分将致力于开发方法，使最优控制理论和实验具有更好的可比性。理论上最优脉冲的高效率是以频谱宽和非常复杂的脉冲为代价的。应发展一种新的时频方法来研究最优控制理论，以考虑实验约束，如脉冲频谱带宽和时间分布。

Ultracold thermal and quantum degenerate gases as truly quantum objects represent ideal candidates for quantum control. The techniques of coherent control which make use of quantum interferences are being introduced to this field only now. Possibilities to actively control ultracold systems with short, shaped laser pulses will be investigated theoretically in this project. Both coherent control schemes and optimal control theory will be utilized. The association of molecules from ultracold atoms will serve as first example to test popular coherent control strategies such as pump-dump schemes and stimulated Raman adiabatic passage. Emphasis will be placed on a realistic treatment of the molecular interactions to allow for comparison with ongoing experiments. Strategies for vibrational cooling will be investigated and the use of shaped laser pulses for quantum computing with ultracold atoms in an optical lattice will be explored. The second part of the project will be devoted to developing methods which allow for a better comparability of optimal control theory and experiments. The high efficiency of theoretical optimal pulses comes at the expense of spectrally broad and very complex pulses. A new timefrequency approach to optimal control theory shall be developed to allow for the incorporation of experimental constraints such as the pulse spectral bandwidth and time profile.