QLC: EAGER: Collaborative Research: Dissecting many-body correlations in matter by quantum process tomography

化学中最根本的重要问题之一是了解电子在分子中的行为。化学家经常利用光与这些电子的相互作用来推断这些信息。与光的相互作用也可能提供关于分子在液体和固体中如何相互作用的深刻信息。例如，分子间的相互作用决定了电子失去光传递给它们的能量的速度有多快，以及它们忘记光吸收过程的速度有多快。然而，这些特性如何依赖于液体和固体中电子与所有其他电子相互作用的细节并不总是很容易用经典物理学完全描述的光来提取。在这个由化学部门化学结构动力学和机制（CSDM-A）项目资助的项目中，佐治亚理工学院的Carlos Silva教授和休斯顿大学的Eric Bittner教授正在开发一种技术，利用服从量子力学的光来克服这些限制。具体来说，他们利用了一次恰好两个光粒子（光子）的纠缠。纠缠意味着从根本上不可能区分相同粒子的性质，无论它们彼此相距多远。当其中一个光子与分子中的电子相互作用后，测量两个纠缠光子的性质。这种方法为化学家提供了新的工具，以了解不同分子中的电子如何相互交流的细节，从而决定液体和固体中重要的集体行为。除了这项研究所涉及的科技创新外，它还作为一个培训平台，为美国的智力资本和科学基础设施做出贡献，其中量子技术的重要性日益增加。技术描述：量子过程层析成像是一种新型材料光学探针，具有明显的潜力，可以隔离多体和多量子相互作用的细节，具有相对于经典非线性光谱和当代量子光谱的独特选择性。当偏振纠缠对中的一个光子与样品相互作用后，纠缠熵的变化，即最初的纯态变成混合量子态的程度被量化。这种变化是由样本中的非线性过程驱动的。该项目的目标是(i)实现一个通用的时间标记量子过程断层扫描装置，以研究共轭分子和聚合物中的多量子过程，以及（ii）开发一个理论形式，调用该技术的量子光学性质以及对材料固有的多体物理的纠缠双光子状态的影响。该奖项反映了美国国家科学基金会的法定使命，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。

One of the most fundamentally important problems in chemistry is to understand how electrons behave in molecules. Chemists often exploit the interaction of light with such electrons to deduce this information. Interaction with light may also provide profound information on how molecules interact each other in liquids and solids. For example, inter-molecular interactions dictate how fast electrons lose the energy transferred to them by light, and how fast they forget about the process of light absorption. Nevertheless, the details of how these properties depend on electronic interactions with all other electrons in liquids and solids is not always easily extractable using light that can be completely described with classical physics. In this project funded by the Chemical Structure Dynamics and Mechanism (CSDM-A) program of the Chemistry Division, Professors Carlos Silva of the Georgia Institute of Technology and Eric Bittner of the University of Houston are developing techniques that take advantage of light that obeys quantum mechanics to overcome these limitations. Specifically, they exploit entanglement of exactly two light particles (photons) at a time. Entanglement means that it is fundamentally impossible to distinguish between the properties of identical particles, regardless of how far they are from each other. The properties of the two entangled photons are measured after one of the two interacts with electrons in molecules. This approach provides new tools for chemists to understand the details on how electrons in different molecules talk to each other in order to dictate important collective behavior in liquids and solids. In addition to the scientific and technical innovations involved in this research, it serves as a training platform to contribute to the intellectual capital and scientific infrastructure of the US, in which quantum technologies is growing in significance. Technical description: Quantum process tomography is developed as a novel materials optical probe, with clear potential to isolate details of many-body and multi-quantum interactions with unique selectivity with respect to classical nonlinear spectroscopy and contemporary quantum spectroscopies. After one photon in a polarization-entangled pair interacts with a sample, the change in entanglement entropy the degree to which the initially pure state becomes a mixed quantum state is quantified. This change is driven by nonlinear processes in the sample. The objectives for this project are (i) to implement a versatile time-tagged quantum-process tomography setup to investigate multi-quantum processes in conjugated molecules and polymers, and (ii) to develop a theoretical formalism invoking the quantum-optical nature of the technique and the effect on the entangled biphoton state of the many-body physics intrinsic to the material.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.