CAREER: Global Quantum Modeling of Topological Nanosystems for Energy-Efficient Devices.

大多数信息处理是使用互补金属氧化物半导体（CMOS）完成的，这是一种基于一系列相互连接的金属氧化物半导体场效应晶体管（MOSFET）的架构。MOSFET是一种非常简单的半导体器件，其中外加电场控制两个电触点之间的电流流动，允许定义有电流流动的“开”状态和没有电流流动的“关”状态。利用这些“开”和“关”状态的特征，就可以定义构成数字信息处理基础的“1”和“0”位。我们的社会越来越依赖于数字信息处理系统，例如电脑、智能手机和电视，用于我们个人和职业生活的方方面面。越来越小的电子设备对提高性能的相关社会需求正在推动MOSFET的小型化。然而，预计未来MOSFET的小型化不仅会导致器件性能的回报递减，而且还会导致器件消耗过多的功率。因此，一个巨大的挑战是设计和实现新的信息处理器件，绕过MOSFET的限制。这个问题的解决方案将需要一个正交的方法，利用新材料和新方法来解决这个功耗问题。在过去的几年里，拓扑系统一直是激烈的理论和实验研究的焦点。拓扑状态是唯一的，因为它们的存在受到系统中存在的潜在对称性的保护，所以除非对称性被打破，否则状态不能被移除。拓扑材料由于其独特的物理性质，有可能对信息处理产生颠覆性的变化。尽管如此，拓扑学研究缺少的一个关键方面是从基础物理转向工程现实世界设备的途径。这项工作将在基础物理学和工程领域建立桥梁，以开发工具来解决关于拓扑材料在纳米尺度上的行为的许多悬而未决的问题，这些问题的答案将最终决定它们在未来纳米系统中的作用，这些纳米系统将消耗更少的功率而牺牲最小的性能。该职业奖提出了一系列的任务，旨在利用令人兴奋的机会，在各种不同的操作条件下研究拓扑纳米系统，以了解其在未来信息处理系统中的适用性。特别是，该奖项旨在了解拓扑纳米系统中的光-物质相互作用和高频响应。数值结果将首次通过将Kadanoff-Baym量子输运方程的时变版本与麦克斯韦电磁旋度方程在三维空间中的完整解耦合来获得。我们将使用这个量子全局建模工具来获得麦克斯韦方程组在电磁照明下如何在3D拓扑材料中被修改的基本理解。此外，我们将运用这些基本反应的知识来理解拓扑材料在未来纳米系统中可能发挥的作用。此外，结合数值方法，将根据详细的数值模拟结果推导出所考虑的每个器件的紧凑模型，以在拓扑纳米器件的物理原理和简单模型之间提供一个强大的桥梁，这些模型对研究人员寻求利用此类器件设计电路架构有用。这种紧凑的模型将使用从基本场论到半经典磁学的各种分析技术推导出来。这项工作的结果不仅将增加对拓扑材料的理论理解及其在未来信息处理系统中的最终适用性，而且还将有助于实验和电路的设计和解释。

The majority of information processing is done using Complementary Metal Oxide Semiconductor (CMOS), an architecture based on a series of interconnected Metal Oxide Semiconductor Field Effect Transistors (MOSFET). The MOSFET is a very simple semiconductor device in which an applied electric field controls electrical current flow between two electrical contacts allowing the definition of "on" states with current flowing and "off" states with no current flow. Using these characteristics of "on" and "off" states, it is possible to then define bits "1" and "0" which form the basis of digital information processing. Our society is becoming increasingly dependent on digital information processing systems used in, e.g., computers, smart phones, and televisions for every aspect of our personal and professional lives. The related societal demand for increased performance from ever-smaller electronic devices is driving the miniaturization of the MOSFET. However, future miniaturization of the MOSFET is predicted to result in not only diminishing returns in device performance, but also in devices that consume too much power. Thus, a grand challenge is to design and implement novel information processing devices that bypass the limitations of the MOSFET. The solution to this problem will require an orthogonal approach that utilizes new materials and new approaches to solve this power consumption problem. In the past several years, topological systems have been the focus of intense theoretical and experimental study. Topological states are unique in the sense that their existence is protected by an underlying symmetry present in the system, so the states cannot be removed unless the symmetry is broken. Topological materials have the potential to make a disruptive change to information processing due to their unique physical properties. Nonetheless, a key aspect missing from topological research is a path to move from basic physics to engineering real-world devices. This work will bridge the fundamental physics and engineering world to develop tools that serve to address the many open questions remain about the behavior of topological materials at the nanoscale, the answers to which, will ultimately dictate their role in future nanosystems that consume less power with minimal sacrifice of performance.This CAREER award sets forth a series of tasks designed to take advantage of the exciting opportunity to study topological nanosystems under a variety of different operating conditions with the stated goal of understanding their applicability in future information processing systems. In particular, the award aims to understand the light-matter interactions and high-frequency responses in topological nanosystems. Numerical results will be attained by, for the first time, coupling the time-dependent versions of the Kadanoff-Baym quantum transport equations to the full solution to Maxwell's electromagnetic curl equations in three spatial dimensions. We will use this quantum global modeling tool to gain a fundamental understanding of how Maxwell's equations are modified in 3D topological materials under electromagnetic illumination. Furthermore, we will apply this knowledge of fundamental responses to understand the role topological materials may play in future nanosystems. Additionally, in conjunction with the numerical approach, compact models for each of the devices considered will be derived based on the results of the detailed numerical simulations to provide a strong bridge between the physical principles of the topological nanodevices and simple models useful to researchers seeking to design circuit architectures utilizing such devices. Such compact models will be derived using a variety of analytical techniques ranging from basic field theory to semi-classical magnetism. The results of this work will not only increase theoretical understanding of topological materials and their ultimate applicability in future information processing systems, but will also help in the design and interpretation of experiments and circuits.