CAREER: Fluctuation-Induced Phenomena in Microstructured Media

职业：微结构介质中波动引起的现象

• 批准号: 1454836
• 负责人: Alejandro Rodriguez
• 金额: $ 50万
• 依托单位: Princeton University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2015
• 资助国家: 美国
• 起止时间: 2015-02-01 至 2020-01-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1454836&HistoricalAwards=false
• 关键词: CAREER; Fluctuation; Induced; Phenomena; Microstructured

NON-TECHNICAL SUMMARYLight can exert a force and carry heat. Although these statements are uncontroversial today, their confirmations were remarkable triumphs a little over a century ago, only a couple of centuries after scientists had finally managed to show that light is a wave and moves at a finite speed, as opposed to appearing instantaneously. Today's extraordinary ability to confine and manipulate laser light at the nanoscale (billionths of a meter) is enabling unprecedented control over the state of small particles and the guiding of information over long distances, leading to breakthroughs in a variety of technological areas, from medical imaging to telecommunications. The increasing miniaturization of small mechanical devices, from accelerometers in mobile phones to pressure sensors in modern tires, is pushing these small systems into regimes where even tiny effects of light brought about by quantum and thermal fluctuations of electric currents, the jittery motion of matter, become important. Most famously, the vibrations of matter give rise to thermal radiation, or the familiar glow of hot objects that underlies many naturally occurring phenomena (such as the heating of the earth by the sun), and emerging technologies (such as energy-harvesting devices which convert solar heat to electricity). The same fluctuations carry momentum and lead to so-called "dispersion" forces that enable geckos to climb walls and also cause static friction between small devices with movable parts.This project will support theoretical and computational research as well as educational initiatives aimed at studying fluctuation effects in unexplored regimes of nano-scale systems. In particular, the research team will develop theoretical methods to understand the role and impact of designable materials on heat transport and quantum forces between bodies with nano-metric features and separations. At these tiny length scales, the fundamental description of structured materials and their interaction with radiation must be modified to account for the increasing role of atomic effects and strong light-matter interactions. This paves the way for the study of emerging experimental and technological regimes in which, like laser light before it, fluctuation effects are used to control the state of nano-devices. Recent and ongoing studies of these phenomena at larger length scales (millionths of a meter) all point to the unavoidable impact of fluctuations on these systems, from heat radiation that is many times larger than that of far-separated objects, to repulsive forces that can be used to levitate objects in vacuum.In addition to increasing the fundamental understanding of many naturally occurring processes, progress in modeling fluctuation interactions will promote technical developments that benefit society, by guiding improvements and applications in nanotechnology, such as micro-electromechanical systems, thin-film microfluidics, thermophotovoltaic energy conversion, and nano-scale cooling. Furthermore, the research team will incorporate the resulting computational techniques in freely available simulation-software packages that promote teaching and learning by students, new researchers, and researchers from developing nations who could not otherwise afford the high start-up costs of developing new numerical tools from scratch.TECHNICAL SUMMARYQuantum and thermal fluctuations of electromagnetic fields lead to a variety of important phenomena, including radiative heat transport and Casimir forces between neutral, macroscopic objects. These effects play a central role in many naturally occurring processes at everyday length scales, including the radiation emitted from the sun and absorbed by the earth, but become particularly pronounced at sub-micron scales where they can reach atmospheric pressures. Recent theoretical developments in modeling fluctuation phenomena between complex, nanostructured surfaces are enabling rigorous explorations of these interactions. While calculations are extremely challenging and come in a bewildering variety of flavors, from formulations based on statistics of fluctuations to expressions based on path integrals and scattering matrices, at its core the problem of modeling fluctuation interactions can be reduced to the calculation of a large and cumbersome number of classical electromagnetic scattering problems. Existing theoretical techniques have been applied at both microscopic and atomistic scales, but fail to account for important effects arising at intermediate scales. This project aims to fill this gap by introducing novel theoretical and computational tools applicable in emerging experimental regimes where the increasing role of atomistic and nonlinear light-matter interactions cannot be ignored. Research thrusts include the study of (1) non-local effects caused by smearing of the electronic response of materials, (2) temperature gradients induced by external stimuli or material anisotropy, and (3) nonlinearities arising from strong light-matter interactions. In particular, this project aims to study heat transport between various classes of nanostructured surfaces with features and separations at the nanometer scale, where non-local effects and temperature gradients can be significant. Techniques based on the volume integral equation of electromagnetic scattering which can handle non-local and inhomogeneous media will be developed and applied to study thermal radiation as well as other important fluctuation effects, including fluorescence and Raman scattering. At high temperatures, the statistics of fluctuations can be significantly modified due to the presence of strong light-matter interactions. The research team will study the impact of such material nonlinearities on the radiation spectra of bodies at and out of equilibrium, where material-mediated coupling between photons at different frequencies can lead to a variety of unusual effects, including phase transitions and line-shape alterations. Finally, the impact of geometry and non-additivity on wetting phenomena in highly non-planar surfaces will be explored, bringing new perspectives and tools to the field of microfluidics.In addition to increasing the fundamental understanding of many naturally occurring processes, progress in modeling fluctuation interactions will promote technical developments that benefit society, by guiding improvements and applications in nanotechnology, such as micro-electromechanical systems, thin-film microfluidics, thermophotovoltaic energy conversion, and nano-scale cooling. The highly interdisciplinary nature of this research, spanning methods and ideas from statistical physics, numerical linear algebra, electromagnetism, and microfluidics, will be a great source of motivation and material to engage students and the general scientific community. Finally, the techniques outlined above will form the core of a free, well-documented, and portable software package enabling study of fluctuation interactions spanning multiple length scales. Such user-friendly packages promote teaching and learning.

光可以产生力并携带热量。尽管这些说法在今天是没有争议的，但在一个多世纪以前，它们的证实是了不起的胜利，仅仅在几个世纪之前，科学家们终于成功地证明了光是一种波，并且以有限的速度运动，而不是瞬间出现。今天，在纳米尺度（十亿分之一米）上限制和操纵激光的非凡能力，使对小颗粒状态的前所未有的控制和远距离信息的引导成为可能，导致从医学成像到电信等各种技术领域的突破。从手机上的加速度计到现代轮胎上的压力传感器，小型机械设备的日益小型化，正将这些小型系统推向这样一个领域：即使是由电流的量子和热波动带来的光的微小影响，物质的抖动运动，也变得重要起来。最著名的是，物质的振动会产生热辐射，或热物体发出的熟悉的光，这是许多自然现象（如太阳对地球的加热）和新兴技术（如将太阳热量转化为电能的能量收集设备）的基础。同样的波动携带动量，导致所谓的“分散”力，使壁虎能够爬墙，也引起带有活动部件的小型装置之间的静摩擦。该项目将支持理论和计算研究以及旨在研究纳米级系统未开发体系中的波动效应的教育倡议。特别是，研究团队将开发理论方法来理解可设计材料对具有纳米特征和分离的物体之间的热传递和量子力的作用和影响。在这些微小的长度尺度上，必须修改结构材料及其与辐射相互作用的基本描述，以考虑到原子效应和强光-物质相互作用日益增加的作用。这为研究新兴的实验和技术机制铺平了道路，在这些机制中，就像之前的激光一样，波动效应被用来控制纳米器件的状态。最近和正在进行的在更大的长度尺度（百万分之一米）上对这些现象的研究都指出，波动对这些系统的影响是不可避免的，从热辐射比距离遥远的物体大很多倍，到可以用来使物体在真空中悬浮的排斥力。除了增加对许多自然发生过程的基本理解外，波动相互作用模型的进展将通过指导纳米技术的改进和应用，如微机电系统、薄膜微流体、热光伏能量转换和纳米级冷却，促进有利于社会的技术发展。此外，研究小组将把由此产生的计算技术纳入免费提供的模拟软件包中，以促进学生、新研究人员和发展中国家的研究人员的教学和学习，否则他们无法承担从头开始开发新的数值工具的高昂启动成本。技术概述电磁场的量子涨落和热涨落导致中性宏观物体之间的各种重要现象，包括辐射热输运和卡西米尔力。这些影响在日常长度尺度上的许多自然发生的过程中起着核心作用，包括太阳发射并被地球吸收的辐射，但在亚微米尺度上变得特别明显，它们可以达到大气压力。最近在模拟复杂的纳米结构表面之间波动现象的理论发展使这些相互作用的严格探索成为可能。从基于波动统计的公式到基于路径积分和散射矩阵的表达式，虽然计算极具挑战性，并且种类繁多，但其核心问题是波动相互作用的建模可以简化为计算大量繁琐的经典电磁散射问题。现有的理论技术已经应用于微观和原子尺度，但未能解释在中间尺度上产生的重要影响。该项目旨在通过引入新的理论和计算工具来填补这一空白，这些工具适用于新兴的实验制度，其中原子和非线性光物质相互作用的作用越来越大，不容忽视。研究重点包括：(1)材料电子响应的涂抹引起的非局部效应，(2)外部刺激或材料各向异性引起的温度梯度，以及(3)强光-物质相互作用引起的非线性。特别是，本项目旨在研究在纳米尺度上具有特征和分离的不同类别的纳米结构表面之间的热传递，其中非局部效应和温度梯度可能是显著的。基于体积积分方程的电磁散射技术可以处理非局部和非均匀介质，并将其应用于研究热辐射以及其他重要的波动效应，包括荧光和拉曼散射。在高温下，由于存在强烈的光-物质相互作用，波动的统计数据可以显著地修改。研究小组将研究这种材料非线性对处于和非平衡状态的物体的辐射光谱的影响，在这种情况下，不同频率的光子之间的材料介导耦合可能导致各种不寻常的效应，包括相变和线形改变。最后，将探讨几何和非加性对高度非平面表面润湿现象的影响，为微流体领域带来新的视角和工具。除了增加对许多自然发生过程的基本理解外，波动相互作用模型的进展将通过指导纳米技术的改进和应用，如微机电系统、薄膜微流体、热光伏能量转换和纳米级冷却，促进有利于社会的技术发展。这项研究的高度跨学科性质，涵盖了统计物理学、数值线性代数、电磁学和微流体学的方法和思想，将成为吸引学生和一般科学界的动力和材料的重要来源。最后，上面概述的技术将形成一个自由的、文档完备的、可移植的软件包的核心，可以研究跨越多个长度尺度的波动相互作用。这种用户友好的软件包促进了教与学。