Molecular Quantum Control and Spectroscopy Using Light-Dressed States

分子的内部自由度，如振动和旋转，以及它们的量子态之间的各种相互作用，产生了丰富的能级结构。双原子分子（有两个原子的分子）是理想的实验，这是不可能的原子，但避免了压倒性的复杂性的多原子分子。该项目利用激光辐射与双原子分子的相互作用来研究能态之间的跃迁强度，调查由镝或其亲属原子组成的双原子分子的电子结构，并创建分子取向。原子之间形成化学键的两种主要方式涉及共享价电子（共价）或价电子从一个原子转移到另一个原子（离子）。在许多情况下，化学键的性质是离子和共价特征的混合。此外，理论预测表明，化学键的特征可以作为包括核间距离在内的各种参数的函数而逐渐变化。计划中的跃迁偶极矩测量探测原子或分子与光相互作用的强度。这种测量提供了一种灵敏的方法来探索共价键和离子键之间的分子电子结构的变化。研究小组还将研究由具有大磁矩的原子形成的双原子分子，如镝和铒，具有非常规的磁性和强各向异性相互作用。这种二聚体分子的电子结构在实验上是完全未知的。这些研究将为理解短核间距范围内的高度各向异性相互作用和实现具有大磁矩的分子的量子气体提供所需的关键数据。该项目的分子取向实验的控制对于研究分子与其他分子和原子的反应具有重要意义。主要研究人员将继续努力在研究生和本科生的研究中吸引不同的物理学学生。由主要研究人员教授的光学和原子，分子和光学物理课程也为感兴趣的化学和生物物理学生提供服务。该项目涉及多共振高分辨率光谱学和量子光学技术的独特组合，用于量子控制的目的。由NSF MRI赠款2018443资助的SolsTiS激光系统为拟议实验中的耦合激光器提供了激光功率，调谐范围和频率稳定性的关键增强。利用缀饰态方法提高了拉比频率，可以控制分子的排列和取向，从而研究碰撞对双原子分子转动角动量的影响。操纵分子的旋转角动量的能力使得有可能获得分子框架信息以及允许控制其速率取决于分子轴的取向的物理和化学过程。此外，这将是可能的探测跃迁偶极矩行为的区域之间的共价非绝热势能函数和离子对电位避免交叉。这些势的相互作用导致跃迁偶极矩的大的变化和有趣的长程势能威尔斯井与密集的能级结构与不寻常的辐射性质。计划中的镧系元素二聚体的高分辨率光谱研究将把原子系统的量子磁性研究扩展到磁矩比原子更大的分子系统。这些实验将为这些重要磁性分子的电子结构的最新理论从头算研究提供关键数据。该奖项反映了NSF的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

The internal degrees of freedom, such as vibrations and rotations, of molecules and the variety of interactions between their quantum states give rise to a rich energy level structure. Diatomic molecules (those with two atoms) are ideal for experiments which are not possible with atoms but avoid the overwhelming complexity of polyatomic molecules. This project utilizes the interaction of laser radiation with diatomic molecules to study the strength of transitions between energy states, investigate the electronic structure of diatomic molecules composed of atoms of dysprosium or its relatives, and create molecular orientation. The two main ways by which chemical bonds are formed between atoms involve sharing of valence electrons (covalent) or a transfer of valence electrons from one atom to another (ionic). In many instances the nature of the chemical bond is a mixture of ionic and covalent character. Furthermore, theoretical predictions indicate that the character of a chemical bond can gradually change as a function of various parameters including the internuclear distance. The planned transition dipole moment measurements probe the strength of the interaction of an atom or a molecule with light. Such measurements provide a sensitive way to explore the changes in molecular electronic structure between covalent and ionic bonding. The research team will also study diatomic molecules formed from atoms with large magnetic moments such as dysprosium and erbium with unconventional magnetic properties and strong anisotropic interactions. The electronic structure of such dimer molecules is completely unknown experimentally. These studies will provide the missing critical data needed for the understanding of highly anisotropic interactions at short internuclear distance range and the realization of quantum gases of molecules with large magnetic moments. The control of molecular orientation experiments of the project will be of importance for the study of reactions of molecules with other molecules and atoms. The principal investigators will continue to strive engaging a diverse set of Physics students in research both at the graduate and undergraduate levels. The Optics and the Atomic, Molecular and Optical Physics courses taught by the principal investigators also serve interested chemistry and biophysics students.This project involves a unique combination of multiple resonance high resolution spectroscopy and quantum optics techniques of dressed molecular quantum states with light for the purposes of quantum control. The SolsTiS laser system funded by the NSF MRI grant 2018443 provides a critical enhancement of laser power, tuning range, and frequency stability for the coupling laser in the proposed experiments. The dressed-states approach with an enhanced Rabi frequency will make it possible to control molecular alignment and orientation to study the effects of collisions on the rotational angular momentum of diatomic molecules. The ability to manipulate the rotational angular momentum of molecules makes it possible to obtain molecular frame information as well as allow control of physical and chemical processes whose rates are dependent on the orientation of the molecular axis. In addition, it will be possible to probe the transition dipole moment behavior in regions of avoided crossings between covalent diabatic potential energy functions and the ion-pair potential. The interaction of these potentials leads to large changes in the transition dipole moment and interesting long range potential energy wells with dense energy level structure with unusual radiative properties. The planned high resolution spectroscopic investigation of the lanthanide dimers will extend the atomic systems quantum magnetism studies to molecular systems with even larger magnetic moments than the atoms. These experiments will provide critical data for recent theoretical ab initio studies of the electronic structure of these important magnetic molecules.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.