QLC: EAGER: Collaborative Research: Developing Experiment and Theory for Entangled Photon Spectroscopy

QLC：EAGER：协作研究：开发纠缠光子光谱的实验和理论

• 批准号: 1836392
• 负责人: George Schatz
• 金额: $ 15万
• 依托单位: Northwestern University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2018
• 资助国家: 美国
• 起止时间: 2018-08-01 至 2021-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1836392&HistoricalAwards=false
• 关键词: QLC; EAGER; Collaborative; Research; Developing

This research project is concerned with understanding unusual phenomena that arise when light interacts with molecules. Light can be thought of as tiny bundles of energy known as photons. In most cases, molecules absorb light energy one photon at a time. This absorption can give rise to things we commonly observe, such as color and fluorescence. The focus of this project is the near-simultaneous absorption of two photons by molecules. Photons normally act independently, but there is a quantum effect in which two photons become entangled, and absorption of one photon becomes strongly dependent on the other photon. We can think of the two photons talking to each other. When this happens, the rate of absorption of two photons can be enhanced by many orders of magnitude. Such enhancements in light absorption could advance many technological applications that range from electronic devices to chemical sensing. However, the details of molecule absorption of entangled photons are poorly understood. The few experiments that have been done on entangled photons do not always produce consistent results, even for similar molecules. In this research project, Professors George Schatz of Northwestern University and Theodore Goodson of the University of Michigan are combing experimental laser-based measurements and computational modeling to study the absorption of entangled photons by molecules. Students and postdocs who work on this project are being trained in new experimental and theoretical techniques that are likely to play a role as new technologies are developed based on these unique quantum effects. In addition, Profs. Schatz and Goodson are engaging in active outreach programs related to their research that touches on broad segments of society.In this project, a quantum optical experimental approach and a quantum electronic computational approach are being applied to investigate new properties of organic molecules that are accessible through entangled two-photon absorption (ETPA). The studies take advantage of the quantum entanglement of photons created by the process of spontaneous parametric down conversion and the subsequent excitation of electronic states in molecules. The phenomenon of ETPA has been theoretically predicted to exhibit interesting non-classical effects such as linear rather than quadratic dependence of absorption rate on incident photon flux. In prior work, Prof. Goodson, demonstrated the surprising result that some molecules show significant ETPA cross sections while other nominally similar molecules show no observable ETPA. To go further, this project employs theory and experiments aimed at understanding intermediate states that participate in ETPA. The theory studies involve calculating transition moments that couple excited states, which is an ability that is generally missing from electronic structure theories. The computational aspect of the project also utilizes a new time-dependent density functional theory (TDDFT) approach developed by Prof. Schatz, for calculating energies and transition moments, and ultimately ETPA cross sections. The computational results are being compared with pump-probe entangled time-resolved measurements using a new apparatus, with the goal of sorting out the role of intermediate states in ETPA. The project is also concerned with training graduate students and postdocs, and enabling them to develop careers of their own that explore directions of the quantum world that have not yet been conceived. In addition, the PIs have active outreach programs where the research described in this proposal is presented at levels that range from graduate courses in quantum mechanics to talks to the general public.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.

这个研究项目是关于理解当光与分子相互作用时出现的不寻常现象。光可以被认为是被称为光子的微小能量束。 在大多数情况下，分子一次吸收一个光子的光能。 这种吸收会产生我们通常观察到的东西，例如颜色和荧光。 该项目的重点是分子几乎同时吸收两个光子。光子通常是独立作用的，但存在量子效应，其中两个光子纠缠在一起，一个光子的吸收强烈依赖于另一个光子。 我们可以想象两个光子在互相交谈。 当这种情况发生时，两个光子的吸收率可以提高许多数量级。 这种光吸收的增强可以推进从电子设备到化学传感的许多技术应用。然而，纠缠光子的分子吸收的细节知之甚少。 对纠缠光子所做的为数不多的实验并不总是产生一致的结果，即使是对类似的分子。 在这个研究项目中，美国西北大学的乔治·沙茨教授和密歇根大学的西奥多·古德森教授正在结合基于激光的实验测量和计算建模来研究分子对纠缠光子的吸收。 参与该项目的学生和博士后正在接受新的实验和理论技术的培训，这些技术可能会在基于这些独特的量子效应开发新技术时发挥作用。此外，教授。Schatz和Goodson正在积极开展与他们的研究相关的广泛的社会推广计划。在这个项目中，量子光学实验方法和量子电子计算方法被应用于研究通过纠缠双光子吸收（ETPA）可以获得的有机分子的新特性。这些研究利用了自发参量下转换过程中产生的光子的量子纠缠以及随后分子中电子态的激发。理论上预测ETPA现象表现出有趣的非经典效应，例如吸收率对入射光子通量的线性而不是二次依赖性。在之前的工作中，Goodson教授证明了令人惊讶的结果，即一些分子显示出显著的ETPA横截面，而其他名义上相似的分子则没有显示出可观察到的ETPA。为了更进一步，该项目采用了旨在了解参与ETPA的中间状态的理论和实验。理论研究涉及计算耦合激发态的跃迁矩，这是电子结构理论中通常缺少的能力。该项目的计算方面还利用了Schatz教授开发的新的含时密度泛函理论（TDDFT）方法，用于计算能量和跃迁矩，并最终计算ETPA截面。计算结果正在与使用新设备的泵浦探测纠缠时间分辨测量进行比较，目的是找出ETPA中中间态的作用。该项目还涉及培训研究生和博士后，使他们能够发展自己的职业生涯，探索尚未构想的量子世界的方向。此外，PI还有积极的外展计划，在这些计划中，本提案中所描述的研究将以从量子力学研究生课程到面向公众的讲座等不同层次进行展示。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。

项目成果

Two-photon excited deep-red and near-infrared emissive organic co-crystals

• DOI: 10.1038/s41467-020-18431-7
• 发表时间: 2020-09
• 期刊: Nature Communications
• 影响因子: 16.6
• 作者: Yu Wang;Huan-Bao Wu;Penghao Li;Su Chen;Leighton O. Jones;Martín A. Mosquera;Long Zhang;K. Cai-K.-Ca

Efficient Modeling of Organic Chromophores for Entangled Two-Photon Absorption

用于纠缠双光子吸收的有机发色团的有效建模

• DOI: 10.1021/jacs.0c02808
• 发表时间: 2020
• 期刊: Journal of the American Chemical Society
• 影响因子: 15
• 作者: Kang, Gyeongwon;Nasiri Avanaki, Kobra;Mosquera, Martín A.;Burdick, Ryan K.;Villabona-Monsalve, Juan P.;Goodson, Theodore;Schatz, George C.
• 通讯作者: Schatz, George C.