Nonequilibrium Quantum Mechanics of Strongly Correlated Systems

强相关系统的非平衡量子力学

• 批准号: 1004589
• 负责人: Aditi Mitra
• 金额: $ 28.5万
• 依托单位: New York University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2010
• 资助国家: 美国
• 起止时间: 2010-09-15 至 2014-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1004589&HistoricalAwards=false
• 关键词: Nonequilibrium; Quantum; Mechanics; Strongly; Correlated

TECHNICAL SUMMARYThis award supports theoretical research and education to advance fundamental understanding of the properties of strongly correlated quantum systems that have been driven far from equilibrium. This research is motivated by experiments on nonequilibrium quantum systems. Using Keldysh diagrammatic methods, the PI has shown how powerful concepts such as mean-field theory, identifying the important fluctuations about mean-field and the renormalization group can be generalized to a variety of nonequilibrium problems. The PI will further build on these ideas and apply them to the following systems:a). Nonequilibrium quantum impurity models which show rich behavior in equilibrium such as non-Fermi liquid physics and quantum phase transitions.b). Spatially extended systems near dissipative quantum critical points and driven out of equilibrium by current flow.c). Strongly correlated systems subjected to strong time dependent perturbations such as a sudden change of a parameter of the Hamiltonian, or by photo-excitation by strong transient light pulses. These projects will be relevant to a number of experimental systems such as: nonequilibrium nanoscale devices, cold atoms in optical lattices with rapidly tunable parameters, nonlinear optical spectroscopies of strongly correlated systems and transport near quantum critical points. Fundamental questions that will be addressed include:a). Systems near equilibrium quantum critical points show universal behavior. Do notions of universality still hold when these systems are driven out of equilibrium?b). To what extent is an "effective temperature" description of nonequilibrium systems valid?c). Can a nonequilibrium drive such as uniform current flow give rise to new kinds of time-independent or time-dependent dynamical phases?d). Is it possible to realize nonequilibrium driven ``ordering-disordering'' quantum phase transitions? If so can such transitions be characterized by universality and critical exponents?This award also supports guidance and training of graduate and undergraduate students in an emerging area of science.NON-TECHNICAL SUMMARY:This award supports theoretical research and education aimed towards understanding many particle systems that require a quantum mechanical description and are out of balance with their surroundings because of a large perturbation. Applying a voltage to electrons in a material with very small dimensions the size of molecules, otherwise known as a nanostructure, would be an example. For these systems, the successful theoretical methods developed to understand and describe systems that are in balance with their surroundings do not work and the PI aims to develop extensions of these equilibrium methods to nonequilibrium systems. This general problem also arises in atomic and optical physics, biological systems, and quantum information theory and the PI's approach should apply to a broad range of nonequilibrium systems. The PI will build on her previous work and study nanostructures out of equilibrium and explore the possibility that an electric current can drive materials that are near a transformation to magnetism or superconductivity into new states of matter that may not exist in equilibrium. She will also study nonequilibrium quantum systems that have many strongly interacting particles, such as strongly correlated materials subjected to intense transient pulses of light.This research contributes to the broad fundamental understanding of the world around us. The focus of the research on nanostructures and systems of impurities contributes to the theoretical foundations that will enable the design of possible future electronic devices and information technology.This award also supports guidance and training of graduate and undergraduate students in an emerging area of science.

技术摘要这一奖项支持理论研究和教育，以促进对远离平衡驱动的密切相关量子系统的性质的基本理解。这项研究是由非平衡量子系统实验的动机。 PI使用Keldysh图解方法，表明了诸如平均场理论之类的强大概念如何确定有关均值场和重新归一化组的重要波动，可以推广到各种非平衡问题。 PI将进一步以这些想法为基础，并将其应用于以下系统：a）。非平衡量子杂质模型，在非Fermi液体物理和量子相变的平衡中表现出丰富的行为。B）。耗散量子临界点附近的空间扩展系统，并通过流动流出驱动。紧密相关的系统受到强烈依赖性扰动的影响，例如汉密尔顿的参数突然变化，或通过强烈的瞬时光脉冲进行照相。这些项目将与许多实验系统有关，例如：非平衡纳米级设备，具有快速可调参数的光学晶格中的冷原子，密切相关系统强的非线性光谱以及量子关键点附近的传输。将要解决的基本问题包括：a）。平衡量子临界点附近的系统显示了普遍的行为。当这些系统被驱逐出平衡时，普遍性仍然存在吗？b）。非平衡系统的“有效温度”描述在多大程度上有效？c）。诸如均匀电流流量之类的非平衡驱动能够产生新型的与时间无关或时间相关的动态阶段？d）。是否可以实现非平衡驱动的``订购disordering''量子相变吗？如果是这样的话，这种过渡的特征是普遍性和关键指数吗？该奖项还支持在科学新兴领域的研究生和本科生的指导和培训。没有技术摘要：该奖项支持理论研究和教育，旨在理解许多需要量子机械描述的粒子系统，并且与周围的环境保持平衡，因为这是一个巨大的扰动。将电压施加到具有很小尺寸的材料中的电子，分子的大小（也称为纳米结构）将是一个例子。对于这些系统，开发了成功的理论方法来理解和描述与周围环境保持平衡的系统，PI旨在将这些平衡方法扩展到非平衡系统。这个一般问题也出现在原子和光学物理，生物系统和量子信息理论中，PI的方法应适用于广泛的非平衡系统。 PI将基于她以前的工作，并以平衡研究纳米结构，并探索电流可以驱动近似磁性或超导性转化为可能不存在的物质状态的材料的可能性。她还将研究具有许多强烈相互作用粒子的非平衡量子系统，例如受到强烈的光线脉冲强烈相关的材料。这项研究有助于对我们周围世界的广泛理解。关于纳米结构和杂质系统的研究重点是理论基础，这些基础将使可能的未来电子设备和信息技术设计。该奖项还支持在科学领域的研究生和本科生的指导和培训。