Driving Quantum Systems with Classical Fields

在半导体器件中控制电子运动的能力是电子学、光子学和声子学的核心，这些基础科学领域导致了能源、通信、传感、信息科学和安全等领域的技术进步。电子是每个原子中都存在的非常小的粒子，它们遵守量子力学定律，这使得与它们相互作用并以高度可预测的方式控制它们的运动具有挑战性。这个项目背后的核心问题是如何利用光和声音，这两种在日常生活中经常遇到的经典波，来激发或驱动现代半导体设备中的电子。这些装置的尺寸只有几纳米，还不到人类头发厚度的千分之一。由于该设备尺寸小且存在不可避免的缺陷，因此理解设备中光和声音如何与电子相互作用比在更大的系统（如块状材料）中回答相同的问题更具挑战性。然而，小的设备尺寸也可能导致惊人的新现象的出现，带来巨大的技术冲击。为此，该项目将开发最先进的模拟软件，以分析纳米级设备中的电子如何与经典光和声音相互作用。以实验为基准的微观理论和精确的模拟工具，例如将在本项目过程中开发的那些工具，对于深化对纳米尺度世界的理解和预测新现象和功能是无价的，所有这些都只需要实验成本的一小部分。这个项目将有利于工业界和学术界的实验团体，帮助他们设计新的设备。这些代码将通过GitHub作为开源发布，以确保广泛使用。在现代纳米结构中，如何利用经典的电磁波或声波来激发或驱动量子电子系统？这个问题贯穿了电子学、光子学和声子学，并具有从能源到通信、传感、信息科学和安全的技术影响。答案需要对表征纳米材料和纳米结构中电荷与光和声音相互作用的物理过程有深刻的理解，并且答案与块体材料中的类似物有很大的不同，因为这些系统的低维和小尺寸导致它们对边界和边缘、无序、周围材料特性的敏感性，并且还可能导致引人注目的新等离子体、极化和激子现象的出现。为此，该项目的目标是开发和部署一种全面的建模方法，采用最先进的经典电磁波和弹性波模拟技术，结合量子电子输运的有效密度矩阵技术，以便在纳米尺度上理解和利用光、声和电荷的相互作用。这项工作将被组织成两个推力，每个推力都以一种经典波为中心。在“推力1：纳米材料中的光-物质相互作用”中，场势时域有限差分计算电磁学的最新算法进展将与使用密度矩阵的量子输运模拟相结合。在这个新的自洽求解器中，量子输运和经典电动力学将在每个时间步长自洽耦合。在“推力2：纳米材料中的声-物质相互作用”一节中，将把无序介质中弹性波散射模拟的最新计算进展与使用密度矩阵的量子电子输运模拟相结合。新的模拟将分析表面声波驱动发光纳米结构中量子电子输运的系统。这些代码将通过GitHub作为开源发布，并将使设计新设备的实验学家受益。本科研究人员也将参与该项目。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。

The ability to control the movement of electrons in semiconductor devices lies at the core of electronics, photonics, and phononics, which are basic-science fields that give rise to technological advances in energy, communication, sensing, information science, and security. Electrons are very small particles found in every atom, and they obey the laws of quantum mechanics, which makes it challenging to interact with them and control their motion in a highly predictable fashion. The central question behind this project is how one can use light and sound, both classical waves commonly encountered in daily lives, to excite or drive electrons in modern semiconductors devices. The size of these devices is a few nanometers, less than a thousandth of the thickness of a strand of human hair. Owing to the device small size and inescapable imperfections, it is much more challenging to understand how light and sound interact with electrons in devices than it is to answer the same question in much larger systems, such as bulk materials. However, the small device size may also lead to the emergence of striking new phenomena with great technological impact. To that end, state-of-the-art simulation software to analyze how electrons in nanoscale devices interact with classical light and sound will be developed during this project. Microscopic theory and accurate simulation tools benchmarked against experiment, such as those that will be developed during the course of this project, are invaluable for deepening the understanding of the world at the nanoscale and for predicting new phenomena and functionalities, all at a fraction of experimental cost. This project will benefit experimental groups in industry and academia by helping design new devices. The codes will be distributed as open source through GitHub to ensure widespread use.How can classical waves, electromagnetic or acoustic, be used to excite or drive quantum electronic systems in modern nanostructures? This question cuts through electronics, photonics, and phononics, and has technological repercussions ranging from energy to communication, sensing, information science, and security. The answer requires a deep understanding of the physical processes that characterize the interplay of charge with light and sound in nanomaterials and nanostructures, and the answer differs greatly from its analogue in bulk materials because the low dimensionality and small size of these systems result in their sensitivity to boundaries and edges, disorder, surrounding materials properties, and may also lead to the emergence of striking new plasmonic, polaronic, and excitonic phenomena. To that end, the objective in this project is to develop and deploy a comprehensive modeling approach, employing state-of-the-art simulation techniques for classical electromagnetic and elastic waves coupled with an efficient density-matrix technique for quantum electronic transport in order to understand and harness the interplay of light, sound, and charge at the nanoscale. The work will be organized into two thrusts, each centered on one type of the classical wave. Under Thrust 1: Light–matter interaction in nanomaterials, recent algorithmic advances in field-potential finite-difference time-domain computational electromagnetics will be integrated with those involving quantum transport simulation using the density matrix. In this new self-consistent solver, quantum transport and classical electrodynamics will be coupled self-consistently and at every time step. Under Thrust 2: Sound-matter interaction in nanomaterials, recent computational advances in the simulation of elastic-wave scattering in disordered media will be integrated with those involving quantum electron transport simulation using the density matrix. The new simulation will analyze systems in which surface acoustic waves drive quantum electronic transport in light-emitting nanostructures. The codes will be distributed as open source through GitHub, and will benefit experimentalists designing new devices. Undergraduate researchers will also take part in this project.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.