Quantum dynamics of two-body, few-body and many-body molecular systems at low temperatures

低温下二体、少体和多体分子系统的量子动力学

• 批准号: RGPIN-2014-06419
• 负责人: Krems, Roman
• 金额: $ 4.95万
• 依托单位: University of British Columbia
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2014
• 资助国家: 加拿大
• 起止时间: 2014-01-01 至 2015-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=567791
• 关键词: Quantum; dynamics; two; body; few

Funding is requested for a theoretical research program that will explore quantum dynamics of binary, few-body and many-body molecular systems in electromagnetic fields. Specifically, the proposed research will be on three topics: (i) low-temperature dynamics of complex polyatomic molecules and controlled chemistry; (ii) polarons in new interaction regimes; and (iii) controlled energy transfer in open quantum systems. Within each of these topics, we will address the most pressing questions at the forefront of current research in physics and chemistry and only consider molecular systems that have been or can soon be experimentally realized. The goal of research direction (i) will be to study the feasibility of buffer gas cooling of hydrocarbon molecules to subKelvin temperatures and to develop tools to explore the unique features of bimolecular chemical reactions of cold molecules in electromagnetic fields. This work will be closely related with the experiments on buffer gas cooling of molecules, an emerging research direction aiming to create new technologies for sensitive detection of trace molecules and the production of high-flux beams of polyatomic molecules slowly moving in the laboratory frame. The research of topics (ii) and (iii) is motivated by the spectacular recent experiments which demonstrated the possibility of synthesizing molecules at temperatures below 1 microKelvin. It was found that ultracold molecules can be very reactive, undergoing chemical reactions at fast rates. It was also demonstrated that ultracold molecules can be trapped in a periodic potential of an optical lattice. Current experiments are focused on improving the trapping fidelity to minimize the effect of disorder, in an effort to produce a periodic, crystal-like system, where molecules are suspended by the laser field potential and intermolecular interactions can be controlled by electromagnetic fields. We will study the realization of the polaron Hamiltonians with molecules trapped in laser fields. Polarons are quasi-particles appearing in the excitation spectra of particles (such as electrons or excitons) coupled to a bosonic field (such as phonons). We will calculate the phase diagram of polarons in the previously unexplored range of particle - field interaction parameters and study the possibility of observing non-linear polaron interactions in the excitation spectra of cold molecules. We will develop computer codes to study the feasibility of the experimental realization of controlled open quantum systems with molecules trapped in optical lattices. The goal will be to propose an experimental system that could be used to study (a) the dynamics of quantum particles coupled to a finite-size bath near a transition between the Markovian and non-Markovian environment; and (b) control mechanisms of energy transport in open quantum systems with controllable, finite-size baths. If our results show that complex organic molecules can be cooled to ultracold temperatures, the research field of cold molecules will greatly expand. Within reach will be the possibility to study tunnelling reactions of biological interest without thermal averaging as well as many fundamental phenomena that cannot yet be studied. Examples include effects of the geometric phase and tunable resonances in chemical dynamics, effects of fine structure on chemical transformations and the role of quantum statistics, or lack thereof, in chemical reactivity. Our study of novel polaron problems will connect molecular spectroscopy and condensed-matter physics in new ways, providing a new stimulus to both research fields. The realization of controllable open systems with trapped molecules may become a new paradigm in the study of few-particle dynamics under dissipation.

需要资助一个理论研究项目，该项目将探索电磁场中二元、少体和多体分子系统的量子动力学。具体来说，拟议的研究将围绕三个主题：（i）复杂多原子分子的低温动力学和受控化学； (ii) 新相互作用机制中的极化子； (iii) 开放量子系统中的受控能量转移。在每个主题中，我们将解决当前物理和化学研究最前沿的最紧迫问题，并且仅考虑已经或即将通过实验实现的分子系统。研究方向（i）的目标是研究缓冲气体将碳氢化合物分子冷却至亚开尔文温度的可行性，并开发工具来探索电磁场中冷分子双分子化学反应的独特特征。这项工作将与分子缓冲气体冷却实验密切相关，这是一个新兴的研究方向，旨在创造灵敏检测痕量分子的新技术，并产生在实验室框架中缓慢移动的多原子分子的高通量光束。主题 (ii) 和 (iii) 的研究是由近期令人惊叹的实验推动的，这些实验证明了在低于 1 微开尔文的温度下合成分子的可能性。研究发现，超冷分子的反应性非常强，能够快速发生化学反应。研究还证明，超冷分子可以被捕获在光学晶格的周期性势中。目前的实验重点是提高捕获保真度，以尽量减少无序的影响，努力产生周期性的晶体状系统，其中分子由激光场电势悬浮，分子间相互作用可以由电磁场控制。我们将研究激光场中捕获分子的极化子哈密顿量的实现。极化子是出现在与玻色子场（例如声子）耦合的粒子（例如电子或激子）的激发光谱中的准粒子。我们将计算先前未探索的粒子场相互作用参数范围内的极化子相图，并研究在冷分子的激发光谱中观察非线性极化子相互作用的可能性。我们将开发计算机代码来研究实验实现分子被困在光学晶格中的受控开放量子系统的可行性。目标是提出一个实验系统，可用于研究（a）耦合到马尔可夫和非马尔可夫环境之间过渡附近的有限尺寸浴的量子粒子的动力学； (b) 具有可控、有限尺寸浴的开放量子系统中能量传输的控制机制。如果我们的研究结果表明复杂的有机分子可以冷却到超冷温度，那么冷分子的研究领域将大大扩展。将有可能在不进行热平均的情况下研究具有生物学意义的隧道反应以及许多尚未研究的基本现象。例子包括化学动力学中几何相位和可调共振的影响、精细结构对化学转变的影响以及量子统计或缺乏量子统计在化学反应中的作用。我们对新极化子问题的研究将以新的方式将分子光谱学和凝聚态物理联系起来，为这两个研究领域提供新的刺激。具有捕获分子的可控开放系统的实现可能成为耗散下少粒子动力学研究的新范式。