Molecular Quantum Control by Coherence Effects

通过相干效应进行分子量子控制

• 批准号: 1607432
• 负责人: A. Marjatta Lyyra
• 金额: $ 46.69万
• 依托单位: Temple University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2016
• 资助国家: 美国
• 起止时间: 2016-09-01 至 2020-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1607432&HistoricalAwards=false
• 关键词: Molecular; Quantum; Control; Coherence; Effects; Molecular; Quantum; Control; Coherence; Effects

This project will use laser light to control molecules, atoms that are chemically bound together. Typically it takes at least two electrons to create a chemical bond between atoms. The spins of these electrons can be parallel (triplet states) or antiparallel (singlet states). This project will use laser light to switch the molecule between a singlet and a triplet state, thus realizing a "spin switch" with potential applications to quantum computing. Additionally, this project will study the collisions of atoms and molecules under well-defined initial conditions. In general, molecules are not spherically symmetric objects and as a result most collisional processes involving them strongly depend on the relative alignment of the colliding partners. This project will use lasers to control this alignment. Understanding the basic physics of collision processes between atoms and molecules is of importance for processes such as chemical reactivity. The mixing of the character of quantum states due to coupling depends on the strength of the interaction as well as on the energy separation between the interacting quantum states. Using the AC Stark effect of a strong control laser to shift the energy levels of a spin-orbit coupled pair of ro-vibrational levels of the Lithium dimer into resonance, the population transfer between a singlet and a triplet state would occur in a controlled fashion in the time domain under the influence of an external optical field. When two states are on resonance (have the same energy) the probability function has an oscillatory time dependence with a period inversely proportional to the coupling strength of the two states. Thus, if the population is initially placed in one of the states and the two states are rapidly brought into resonance only for the duration of half integer oscillatory periods, and then rapidly moved off resonance, the population will effectively switch from one of the states to the other one. The electric field amplitude of the control laser is determined by the resonance condition of the two states, and the pulse duration by their oscillatory period. The kinetics and dynamics of collisions between alkali molecules and noble gas atoms will be studied under well-defined initial conditions of molecular alignment created using the AC Stark effect of a control laser. The orientation will be achieved by removing the degeneracy of the magnetic sublevels using the orientation dependence of the transition dipole moment. The magnetic sublevels are projections of the total angular momentum of the molecule on a laboratory fixed axis defined by the polarization direction of the resonant laser field. For sufficiently large control laser Rabi frequencies, the sublevels will be separated well enough so specific quantized orientations of the molecules of one or more rotational quantum states can be probed and the collisional transfer between them studied. An advantage of this method is that it will allow for selective removal of the magnetic sublevel degeneracy in contrast to cases where external magnetic or electric fields are used.

该项目将使用激光来控制分子，这些原子在化学上结合在一起。 通常，至少需要两个电子才能在原子之间建立化学键。这些电子的旋转可以是平行的（三重态）或反平行的（单重状态）。该项目将使用激光灯在单线和三胞胎状态之间切换分子，从而意识到具有潜在应用量子计算的“自旋开关”。此外，该项目将在定义明确的初始条件下研究原子和分子的碰撞。通常，分子不是球面对称对象，因此，大多数涉及它们的碰撞过程都在很大程度上取决于碰撞伴侣的相对对准。该项目将使用激光来控制此对齐。了解原子和分子之间碰撞过程的基本物理学对于化学反应性等过程至关重要。由于耦合而引起的量子状态特征的混合取决于相互作用的强度以及相互作用量子状态之间的能量分离。使用强控制激光器的AC鲜明效应，将锂二聚体的一对旋转轨道耦合对的能量水平转移到共振中，单线和三胞胎状态之间的种群转移将以受控的方式发生在外部光学场的影响下。当两个状态保持共振（具有相同的能量）时，概率函数具有振荡时间的依赖性，而周期与两种状态的耦合强度成反比。因此，如果最初将人口放置在一个州之一，并且两个州仅在一半整数振荡期间迅速引起共鸣，然后迅速摆脱共鸣，人口将有效地从一个州切换到另一个州。对照激光器的电场幅度取决于两个状态的共振条件，并在脉冲持续时间之前按其振荡时间确定。在使用对照激光器的AC鲜明效应产生的分子比对的初始条件下，将研究碱分子与贵重原子之间碰撞的动力学和动力学。通过使用过渡偶极矩的方向依赖性去除磁性的磁性脱位来实现方向。磁性上的磁性是分子在实验室固定轴上的总角动量的投影，该轴是由谐振激光场的极化方向定义的。对于足够大的对照激光狂犬频率，可以很好地分离出分离的分离，因此可以探测一个或多个旋转量子状态的分子的特定量化方向，并研究它们之间的碰撞转移。这种方法的一个优点是，与使用外部磁场或电场的情况相比，它将允许选择性去除磁性级别的退化。