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Quantum control of atoms and molecules.

机译：原子和分子的量子控制。

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In this thesis, we introduce a different and simple approach to controlling quantum systems. We show that the quantum-control problem can be greatly simplified by simply limiting the duration of the driving force to less than one characteristic period of the system. (For an atomic-electron Rydberg wave packet this would be the Kepler period, for example, or the vibrational period in the case of a molecule.) If the target state is a bound state of the system, then for times less than the characteristic period, the particle does not have the opportunity to reach the system's boundary and acts essentially as a classical free particle. Such a restriction on the duration of the driving field allows an analytic solution to be found, even in the nonperturbative regime. This analytic solution helps clarify some of the differences between the perturbative and the nonperturbative regimes of excitation. We also show that our solution is nonunique, and the quantum controller has a multiplicity of solutions to chose from.; We will discuss the technique with respect to the hydrogen atom and diatomic molecules, but it can be readily extended to a variety of systems consisting of a lower and an upper manifold of eigenstates.; In particular to the case of molecules, in the nonperturbative regime, population may get trapped in the lower manifold due to the large bandwidth of the exciting pulse. We show that population trapping is avoided by choosing among the many possible solutions one with the longest possible duration, and yet, shorter than the vibrational period of the system.; The validity of our solution is tested by comparison with a direct numerical integration of Schrödinger's equation, and it is found to yield the target state and population transfer with very high accuracy in both regimes of excitation.; We also report on the experimental detection of cold molecules, formed in a magneto-optical trap, with ultrashort-optical pulses.
机译：在本文中，我们介绍了一种控制量子系统的简单方法。我们表明，通过简单地将驱动力的持续时间限制为小于系统的一个特征周期，可以大大简化量子控制问题。 （对于原子电子的里德堡波包，例如，这将是开普勒周期，或者对于分子来说是振动周期。）如果目标状态是系统的束缚状态，则其时间比特征时间小在此期间，粒子没有机会到达系统的边界，并且基本上充当了经典的自由粒子。即使在非扰动状态下，对驱动场持续时间的这种限制也允许找到解析解。该分析解决方案有助于弄清激励的摄动和非摄动机制之间的某些差异。我们还证明了我们的解不是唯一的，并且量子控制器有多种解可供选择。我们将讨论关于氢原子和双原子分子的技术，但是它可以很容易地扩展到由本征态的上下歧管组成的各种系统。特别是对于分子的情况，在非微扰状态下，由于激发脉冲的大带宽，种群可能会陷入较低的歧管中。我们表明，通过在许多可能的解决方案中选择一种具有最长持续时间，但比系统的振动周期短的解决方案，可以避免人口陷阱。通过与Schrödinger方程的直接数值积分进行比较，测试了我们解决方案的有效性，发现在两种激励方式下，该状态都能非常准确地产生目标状态和种群转移。我们还报告了在磁光阱中形成的具有超短光脉冲的冷分子的实验检测。

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