The Impact of Chirped Pulse Millimeter-Wave Technology on the Spectroscopy, Dynamics, and Manipulation of Molecules in Rydberg States

麻省理工学院的Robert Field教授得到化学结构，动力学和机制计划的支持，开发实验方法，利用啁啾脉冲毫米波（CPmmW）辐射与激发分子中的大Rydberg-Rydberg跃迁矩（kilo-Debye）的相互作用。 基于CPmmW的方法将能够开发有效填充核心非穿透Rydberg态的方案，这在一定程度上是由于其巨大的过渡时刻和相对较长的寿命（1微秒）而特别感兴趣。 CPmmW光谱的关键特征是，里德伯-里德伯跃迁直接通过自由感应衰减（FID）信号检测，当CPmmW脉冲极化落在ca内的所有二能级系统时产生。啁啾的10 GHz宽频谱区域（单个10纳秒持续时间CP中的10^5个分辨率元素）。 这种NMR类方案大大上级脉冲超声分子束光谱中普遍使用的单分辨率元素一次间接检测方案。 实验光谱的解释将在多通道量子亏损理论（MQDT）的背景下进行，MQDT是一种基于超越氢的散射框架，用于组装，解释和外推分子电子结构的所有信息。 它的基石是通道，每个通道由无限多的电子态组成，而不是波恩-奥本海默势能曲线。 虽然量子亏损矩阵元素提供了结构和动力学的紧凑的数值描述，编码在这些矩阵元素的基本物理意义仍然模糊。 该项目最雄心勃勃的目标是揭示超越数值MQDT矩阵元素的更紧凑的物理表示。 非穿透核的里德堡态是一种被忽视的物质状态。 对它们独特性质的了解和利用将点燃从基础科学到实际应用等领域的研究。 例如，MQDT可以提供分子结构和动力学的完整图像，这对于分子电子器件和量子计算的发展至关重要。 菲尔德教授希望继续为光谱学家、光谱数据的用户和其他科学领域基于光谱的方法的创造者提供帮助。 他热衷于分享他对分子内动力学如何在光谱奥秘中编码的独特见解，并设计出优雅简单的实验方法来询问和利用不适合简单教科书概念化的分子。 现场实验室的学生和博士后面临的挑战是设计原创实验，为他们的非常规光谱建立非常规拟合模型，并进行严格但基于直觉的量子力学和量子光学计算。 菲尔德研究小组的成员带着自信、直觉和远见离开了麻省理工学院，以制定和解决基础和应用问题。

Professor Robert Field of MIT is supported by the Chemical Structure, Dynamics, and Mechanisms Program to develop experimental methods that exploit the interaction of Chirped Pulse millimeter wave (CPmmW) radiation with large Rydberg-Rydberg transition moments (kilo-Debye) in excited molecules. The CPmmW-based approach will enable the development of schemes for efficiently populating core-nonpenetrating Rydberg states, which are of special interest in part because of their enormous transition moments and relatively long lifetimes ( 1 microsecond). The crucial feature of CPmmW spectroscopy is that Rydberg-Rydberg transitions are detected directly via the Free Induction Decay (FID) signal that results when the CPmmW pulse polarizes all two-level systems that fall within the ca. 10 GHz wide spectral region of the chirp (10^5 resolution elements in a single 10 nanosecond duration CP). This NMR-like scheme is vastly superior to the single-resolution- element-at-a-time indirect detection schemes that are universally used in pulsed supersonic molecular beam spectroscopy. The interpretation of experimental spectra will be done in the context of Multichannel Quantum Defect Theory (MQDT), which is a beyond-Hydrogen, scattering-based framework for assembling, interpreting, and extrapolating all information about the electronic structure of a molecule. Its building blocks are channels, each comprised of an infinite number of electronic states, rather than Born-Oppenheimer potential energy curves. Although the quantum defect matrix elements provide a compact numerical description of structure and dynamics, the fundamental physical meanings encoded in these matrix elements remain obscure. The most ambitious objective of this project is to uncover the more compact physical representation that lies beyond the numerical MQDT matrix elements. Core-nonpenetrating Rydberg states are a neglected state of matter. Knowledge and exploitation of their unique properties will ignite research in areas ranging from fundamental science to practical applications. For example, MQDT can potentially provide a complete picture of the structure and dynamics of a molecule, which will be essential for the development of molecular electronic devices and quantum computing. Professor Field expects to continue providing assistance to spectroscopists, users of spectroscopic data, and creators of spectrum-based approaches in other areas of science. He has a passion for sharing his unique vision of how intramolecular dynamics is encoded in spectroscopic arcanae, and for devising elegantly simple experimental methods to interrogate and exploit molecules that are not amenable to simple, textbook conceptualization. Students and postdocs in the Field laboratory are challenged to design original experiments, build unconventional fit models for their unconventional spectra, and perform rigorous yet intuition-based quantum mechanical and quantum optics calculations. Members of Field's research group leave MIT with the confidence, instincts, and vision to formulate and solve both fundamental and applied problems.