Studies of the Control of Quantum Dynamics

斯图尔特·赖斯得到了理论和计算化学计划的资助，继续他在量子多体系统演化控制理论方面的工作，并将其应用于选择性增强化学反应产物。将继续进行四个领域的研究：1)Kobrak-莱斯光选择绝热通过方案的改进和扩展；2)激发分子简化动力学描述的准确性；3)嵌入溶剂中的分子演化的控制；以及4)在量子动力学可控制的范围内可能存在的基本极限。许多相干控制的理论方法将作为广义受激拉曼绝热通道(StiRAP)过程的扩展，用于控制反应中的产物选择性。在整个化学发展过程中，一直在寻求实现对反应中产物形成的选择性控制。到目前为止，这种控制只能在宏观水平上完成，通过控制外部因素，如温度、压力、溶剂性质等。随着可调谐激光的出现，人们希望能够在微观水平上控制产品的选择性，并选择性地破坏分子中的单个键。人们很快发现，被分子吸收的能量不容易集中在单个键中，而是倾向于在整个分子中重新分配。然而，最近，激光选择化学的概念得到了重生，赖斯和其他人发展的理论表明，通过仔细选择指定形状的复杂激光脉冲序列，可以实现能量局部化。如果这一理论能够在实验上付诸实践，仍有可能实现化学反应微观选择性控制的目标。

Stuart Rice is supported by a grant from the Theoretical and Computational Chemistry Program to continue his work on the theory of control of the evolution of quantum many body systems with applications to the selective enhancement of products of a chemical reaction. Four areas of study will be pursued: 1) refinements and extensions of the Kobrak-Rice photoselective adiabatic passage scheme; 2) the accuracy of reduced dynamical descriptions of an excited molecule; 3) the control of the evolution of a molecule embedded in a solvent; and 4) the possible existence of a fundamental limit to the extent of control of quantum dynamics that is attainable. Much of the theoretical approach to coherent control will be developed as an extension to the generalized Stimulated Raman Adiabatic Passage (StiRAP) process for control of product selectivity in a reaction.The achievement of selective control of product formation in a reaction has been sought persistently throughout the evolution of chemistry. To date, such control has only been accomplished at the macroscopic level, by the manipulation of external factors such as temperature, pressure, solvent character, etc. With the advent of the tunable laser, it was hoped that product selectivity could be controlled at the microscopic level, and that individual bonds within a molecule could be selectively broken. It was very quickly found that energy absorbed by a molecule was not easily localized in individual bonds, but preferred to redistribute throughout the molecule. More recently, however, the concept of laser selective chemistry has had a rebirth, and theories developed by Rice and others have shown that energy could be localized by carefully choosing a complex sequence of laser pulses of prescribed shapes. If this theory can be put to practice experimentally, it may still be possible to realize the goal of microscopic selective control of chemical reactions.