Strong Field Quantum Control

电子和原子在与光场相互作用过程中的运动是量子物理学的重要而困难的挑战之一。量子计算的标准方法是基于简化的假设，这些假设在分子吸收强光、强烈碰撞或受到其他强电场作用的关键时刻失效。如果没有这些简化，即使对于中等大小的分子，计算也变得难以处理，并且分子中原子运动和电子运动之间的基本联系也没有得到很好的理解。该项目中量子控制研究的目标是使用强场将量子过程导向所需的目标，例如重新排列分子中的键。使用强场的控制方法可以通过使用强大的技术来克服上述复杂性，例如学习反馈算法，该算法自动重新编程实验驱动场以寻求优化目标产率而无需计算指导。该项目探索了三种提高量子控制有效性的新方法。首先是一个新的概念框架，称为量子共振环，可以帮助我们理解多体量子问题。第二个改进是将模式识别技术应用于量子控制中的高维问题。第三个改进是将激光控制研究扩展到使用新的X射线激光源。在更广泛的背景下，量子控制研究将最终导致更好地理解电子在分子转化和化学中的作用。电子运动被认为是纳米材料、化学科学和能源技术领域进步的关键问题。因此，从这项工作中获得的见解可能会影响一些问题，如新的光催化剂的能量转换效率;寻找从水中有效提取氢的催化剂;或开发可持续的生物燃料技术。量子控制也是量子信息新领域的基础技术。未来可扩展的量子计算机或量子信息传输系统将依赖于量子控制进行门操作和纠错。一些最有前途的实现涉及使用电子作为量子比特和激光作为控制场，因此在强激光场存在下获得的关于电子量子控制的知识可以直接应用。

The motion of electrons and atoms during and immediately following their interaction with light fields is one of the important and difficult challenges of quantum physics. The standard methods of quantum calculations that underpin most current understanding of molecular structure are based on simplifying assumptions that break down at critical times when molecules absorb intense light, collide strongly, or are subjected to other strong electric fields. Without these simplifications, the calculations become intractable even for molecules of modest size, and the basic connections between atomic motion and electron motion in molecules are not well understood. The goal of the quantum control research in this project is to use strong fields to direct quantum processes towards desired targets, such as rearranging the bonds in a molecule. Control methods using strong fields can overcome the complexities described above, through the use of powerful techniques such as learning feedback algorithms that automatically reprogram the experimental driving fields to seek to optimize the target yield without guidance from calculations. This project explores three new ways to improve the effectiveness of quantum control. The first is a new conceptual framework called a Quantum Resonance Ring that could help our understanding of many-body quantum problems. The second improvement is to apply the techniques of pattern recognition to the high-dimensional problems in quantum control. The third improvement is to extend laser control investigations to use newly available x-ray laser sources. In a broader context, quantum control research will ultimately lead to a better understanding of the actions of electrons in molecular transformation and chemistry. Electron motion is considered a gateway problem for progress in areas of nano-materials, chemical science, and energy technologies. Insights gained from this work could therefore influence problems such as the energy conversion efficiency of new photovoltaics; the search for a catalyst to efficiently extract hydrogen from water; or the development of sustainable biofuel technologies. Quantum control is also the fundamental technology in the new field of quantum information. Future scalable quantum computers or quantum information transfer systems will rely on quantum control for gate operations and for error correction. Some of the most promising implementations involve the use of electrons as qubits and lasers as control fields, so the knowledge gained about quantum control of electrons in the presence of strong laser fields could be directly applicable.