Quantum Critical Phenomena and Non Fermi Liquid Physics

量子临界现象与非费米液体物理

• 批准号: 1006282
• 负责人: Andrew Millis
• 金额: $ 41.4万
• 依托单位: Columbia University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2011
• 资助国家: 美国
• 起止时间: 2011-01-01 至 2015-03-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1006282&HistoricalAwards=false
• 关键词: Quantum; Critical; Phenomena; Non; Fermi

TECHNICAL SUMMARYThis award supports theoretical research and education to elucidate the principles governing the behavior of materials exhibiting novel electronic orders such as forms of superconductivity and magnetism, to develop the methods needed to reliably calculate these properties, and to apply the knowledge to design and control materials with desired properties.A focus of the research is to further develop and more widely apply new computational methods which have been recently introduced. These "continuous time quantum Monte Carlo" methods have opened up wide classes of previously intractable problems to quantitative investigation. The PI will further improve the methods and use them to gain understanding of the properties of high temperature superconductors and other materials with properties that are beyond those of the standard Landau-Fermi liquid concept. Another theme of the research concerns the properties of materials driven out of equilibrium by a current, voltage, or high intensity optical excitation. Developing a general theory of the nonequilibrium domain raises fundamental intellectual challenges, is essential for understanding the properties of nanoscale devices and has impact on solar energy generation. The PI also aims to advance understanding of quantum criticality. Materials near a quantum critical point typically exhibit large amplitude, long range, slowly changing fluctuations, leading to large deviations from the predictions of Landau-Fermi liquid theory.This project will contribute to the training of young scientists who can look at problems from a broad perspective, combining fundamental insights with concrete applications. The PI is active in organizing and lecturing at summer schools where the ideas generated in condensed matter theory are brought to a wider range of scientists.NONTECHNICAL SUMMARYThis award supports theoretical research and education to illuminate fundamental questions such as: How do electrons and atoms, the simple constituents which make up the world around us, combine to produce the astounding variety of behavior found in natural materials? How do we understand these phenomena and control them to produce new kinds of devices and new technologies? The PI will further develop new advanced computational tools and use them to study models of high temperature superconductor materials that exhibit unusual electronic properties in the metallic state that give way to exotic forms of superconductivity as the temperature is lowered. The metallic state of these materials does not conform to the standard model for electrons in metals at low temperatures. In a superconducting state, electrons organize themselves in such way that they can conduct electricity without dissipation. Like the metallic state, superconductivity in high temperature superconductors is also unusual. The PI will explore whether close proximity to a quantum phase transition which occurs at the absolute zero of temperature might be responsible for the unusual features of high temperature superconductors. A quantum phase transition involves the transformation from one state of matter to another driven by the quantum mechanical fluctuations of Heisenberg's uncertainty principle, as opposed to thermal fluctuations which drive more familiar phase transformations like water to steam. The PI will also advance our understanding of systems of many interacting particles that are driven far from the balance of equilibrium, as might occur from a voltage applied to the electrons in small structure of atoms or molecules.The research may have impact across disciplines, including the fields of condensed matter physics, materials science, and electrical engineering. It contributes to the foundations of possible new device technologies at the nanoscale - the scale of atoms and molecules.This project also contributes to the training of young scientists to enable them to combine fundamental insights with concrete applications. The PI is active in organizing and lecturing at summer schools where the ideas generated in condensed matter theory are brought to a wider range of scientists.

该奖项支持理论研究和教育，以阐明表现出新的电子秩序（如超导性和磁性形式）的材料行为的原理，开发可靠计算这些特性所需的方法，研究的重点是进一步发展和更广泛地应用新的计算方法，是最近引进的。这些“连续时间量子蒙特卡罗”方法为定量研究开辟了大量以前棘手的问题。PI将进一步改进这些方法，并使用它们来了解高温超导体和其他材料的特性，这些材料的特性超出了标准朗道-费米液体概念的范围。该研究的另一个主题涉及由电流、电压或高强度光激发驱动的材料的性质。发展非平衡域的一般理论提出了基本的智力挑战，对于理解纳米器件的特性至关重要，并对太阳能发电产生影响。PI还旨在促进对量子临界性的理解。量子临界点附近的物质通常表现出大幅度、长范围、缓慢变化的波动，导致与朗道-费米液体理论的预测有很大的偏差。本项目将有助于培养能够从广阔的角度看待问题的年轻科学家，将基本见解与具体应用相结合。PI积极组织暑期学校，并在暑期学校授课，将凝聚态理论中产生的想法带给更广泛的科学家。非技术性总结该奖项支持理论研究和教育，以阐明基本问题，如：电子和原子，组成我们周围世界的简单成分，如何联合收割机结合，产生自然材料中发现的令人惊讶的各种行为？我们如何理解这些现象，并控制它们来生产新的设备和新的技术？PI将进一步开发新的先进计算工具，并使用它们来研究高温超导材料的模型，这些材料在金属状态下表现出不寻常的电子特性，随着温度的降低，这些材料会让位于奇异的超导形式。这些材料的金属状态不符合低温下金属中电子的标准模型。在超导状态下，电子以这样的方式组织自己，即它们可以导电而不耗散。像金属状态一样，高温超导体中的超导性也是不寻常的。PI将探索在绝对零度下发生的量子相变是否可能导致高温超导体的不寻常特征。量子相变涉及由海森堡不确定性原理的量子力学波动驱动的从一种物质状态到另一种状态的转变，而不是驱动更熟悉的相变（如水到蒸汽）的热波动。PI还将推进我们对许多相互作用粒子系统的理解，这些粒子被驱动远离平衡态，就像在原子或分子的小结构中施加电压时可能发生的那样。该研究可能会对跨学科产生影响，包括凝聚态物理学，材料科学和电气工程领域。该项目有助于为可能的纳米级（原子和分子尺度）新器件技术奠定基础，还有助于培训年轻科学家，使他们能够将联合收割机的基本见解与具体应用相结合。PI积极组织和在暑期学校讲课，在凝聚态理论中产生的想法被带到更广泛的科学家。