CAREER: Decoherence, Non-Equilibrium Properties and Stark Control of Electrons at the Nanoscale

罗切斯特大学的伊格纳西奥佛朗哥获得了化学系化学理论、模型和计算方法项目的职业奖，以研究通过利用量子力学效应对物质中电子和电子性质进行激光控制的基本限制，这是一个被称为量子控制的研究领域。重点是激光而不是更传统的手段（例如，所施加的电压或热力学控制变量的变化），因为激光器提供了在超快时间尺度上（大约十亿分之一秒的百万分之一）变化的可能性。例如，佛朗哥小组研究了现有最快的电流产生方法的微观起源，以及激光将绝缘材料转化为瞬态金属的能力。除了在基本层面上的兴趣，推动电子特性可以控制的时间限制有可能催化化学，光谱学，光电器件设计，通过电信号进行通信以及基于电子特性及其控制的任何其他科学或技术的变革性进展。Franco教授正在通过主动学习方法重新设计研究生水平的量子力学化学教学来影响研究生教育。通过这个项目，他为罗切斯特大学化学专业的顶尖国际本科生创造了暑期研究机会，为培养多元化的、全球参与的美国科学和工程人才做出了贡献。具体来说，Franco小组提高了使用高强度和中等强度超快激光脉冲来操纵纳米级物质的电子特性和动力学的能力。该小组的愿景是建立适用于被激光场驱动远离平衡的物质的结构-功能关系，并推动电子控制的极限。历史上阻碍电子量子控制进展的一个基本限制是由电子-核相互作用引起的超快电子退相干过程对控制的有害影响。为了克服这一限制，Franco教授和他的研究小组：（i）识别、建模和量化电子相干性损失的基本机制，作为设计避免或利用退相干的激光控制方案的必要步骤。(ii)开发基于动态斯塔克效应的激光控制电子的新途径，该动态斯塔克效应由对退相干具有鲁棒性的中等强度（非微扰但非电离）的非共振激光场引起。总之，这些发展促进了新型控制实验，超快光电技术和一类新型动态电子材料的设计，这些材料具有在飞秒时间尺度上可调的有效激光诱导特性。 该项目结合了一个综合的研究和教育计划，为学生提供了一个独特的机会，在化学，物理，纳米科学和光学之间的接口进行跨学科培训和协作工作。这项工作影响研究生教育，通过建议重新设计研究生水平的量子力学化学教学，结合积极的学习方法，如翻转教室和同伴学习解决问题的会议。

Ignacio Franco of the University of Rochester is supported by a CAREER award from the Chemical Theory, Models and Computational Methods program in the Chemistry Division to investigate the fundamental limits in the laser control of electrons and electronic properties in matter by exploiting quantum mechanical effects, an area of research known as quantum control. The focus is on lasers rather than more conventional means (e.g., an applied voltage, or changes in thermodynamic control variables) because lasers offer the possibility of change on an ultrafast timescale (on the order of a millionth of one billionth of a second). The Franco group investigates, for instance, the microscopic origin of the fastest existing method for the generation of currents, and the ability of lasers to turn insulating materials into transient metals. In addition to interest at a fundamental level, pushing the time limit in which electronic properties can be controlled has the potential to catalyze transformative progress in chemistry, spectroscopy, optoelectronic device design, communication through electrical signals, and any other science or technology based on electronic properties and their control. Professor Franco is impacting graduate education by redesigning the teaching of graduate level Quantum Mechanics in Chemistry through active learning pedagogies. With this project, he contributes to the development of a diverse, globally-engaged, U.S. science and engineering workforce by creating summer research opportunities for top international undergraduate students in Chemistry at the University of Rochester.Specifically, the Franco group advances the capabilities of using high and intermediate intensity ultrafast laser pulses to manipulate electronic properties and dynamics in nanoscale matter. The vision of the group is to establish structure-function relations that apply to matter driven far from equilibrium by laser fields, and to push the limit in which control of electrons is exerted. A fundamental limit that has historically hindered progress in the quantum control of electrons is the deleterious effects on the control introduced by ultrafast electronic decoherence processes arising from electron-nuclear interactions. To overcome this limit, Professor Franco and his research group: (i) Identify, model, and quantify basic mechanisms for electronic coherence loss, as a necessary step in the design of laser control scenarios that either avoid or take advantage of the decoherence. (ii) Develop novel routes for laser control of electrons based on the Dynamic Stark Effect induced by non-resonant laser fields of intermediate intensity (non-perturbative but non-ionizing) that are robust to decoherence. Together, these developments catalyze the design of novel control experiments, ultrafast opto-electronic technologies, and a new class of dynamic electronic materials with effective laser-induced properties tunable on a femtosecond timescale. This project incorporates an integrated research and educational plan that provides students with a unique opportunity for interdisciplinary training and collaborative work at the interface between Chemistry, Physics, Nanoscience and Optics. The work impacts graduate education, through a proposed redesign of the teaching of graduate level Quantum Mechanics in Chemistry by incorporating active learning pedagogies, such as flipped classrooms and peer learning problem solving sessions.