Unconventional Quantum Phase Transitions

该奖项支持理论和计算研究和教育，以推进对量子相变的理解，并将其扩展到朗道-金兹堡-威尔逊范式之外。PI将探索几种非常规量子相变，重点关注四个独立但相关的领域。强无序量子相变：受氮-钒、铈-钯-铑和锶-钌酸钙化合物实验的启发，该项目旨在发展一种巡回铁磁量子相变的稀有区域效应理论。他还将研究随机性对一阶量子相变的影响以及无序相关的影响。层状系统中的新相和转变：PI将研究在超冷气体或纳米结构材料中产生的随机和准周期性层状超导体和超流体中出现的不寻常相和转变。量子临界点的动力学和输运：PI将研究超导钼锗和铌纳米线在超导金属量子相变中的电导率。他还将研究铁磁格里菲斯相中的电子输运杂质问题中的Berry相和渗透转变：PI计划分析Berry相对杂质量子相变的量子到经典映射的影响，以及它们对转子和自旋的渗透转变的影响。将采用分析技术和计算机模拟相结合的方法进行研究。该奖项还支持在每年秋天物理学、化学、生理学或医学奖公布后举办一系列“诺贝尔奖讲座”的努力。本系列讲座将由密苏里理工大学物理系、化学系和生物科学系联合举办。他们将对该奖项背后的科学原理进行初步介绍。自2007年以来，PI组织了一系列关于物理学奖的成功讲座，这些讲座将扩大这些讲座。拟议的工作还将加强密苏里理工大学的研究和教育基础设施，因为由PI设计和建造的Pegasus计算机集群将成为物理系计算研究的中心。该奖项支持理论和计算研究和教育，旨在促进对一种相变的理解，这种相变发生在温度为绝对零度的材料中，称为量子相变。不像我们熟悉的相变，例如水到蒸汽的转变是由热波动驱动的，量子相变是由量子力学波动驱动的，这是海森堡测不准原理的结果。量子相变很重要，因为它们的影响可以延伸到温度，可能高达室温甚至更高，并深刻地改变材料中电子的行为。这对电子组织成物质状态的方式产生了影响，比如磁性和超导性，以及其他被预测在电子相互作用强烈的材料中会发生的奇异状态。也许不太熟悉的超导状态具有不寻常的特征，即能够导电而不损失能量以耗散。这导致了在电力传输方面的潜在应用。已知的超导材料只在低温下才表现出超导性，有些材料的温度高达大气中氧气和氮气等气体为液体的温度。更好地理解量子临界现象可能有助于发现在更高温度下表现出超导性的材料。量子相变的严格描述是在标准相变理论之外的。本研究为相变研究开辟了新的领域。量子相变也可能对开发基于量子力学状态操纵的量子计算机以及涉及比人类头发直径小数万倍的元素的纳米级技术产生重要影响。该奖项还支持在每年秋天物理学、化学、生理学或医学奖公布后举办一系列“诺贝尔奖讲座”的努力。本系列讲座将由密苏里理工大学物理系、化学系和生物科学系联合举办。他们将对该奖项背后的科学原理进行初步介绍。自2007年以来，PI组织了一系列关于物理学奖的成功讲座，这些讲座将扩大这些讲座。拟议的工作还将加强密苏里理工大学的研究和教育基础设施，因为由PI设计和建造的Pegasus计算机集群将成为物理系计算研究的中心。

TECHNICAL SUMMARYThis award supports theoretical and computational research and education to advance understanding of quantum phase transitions and broaden it beyond the Landau-Ginzburg-Wilson paradigm. The PI will explore several classes of unconventional quantum phase transitions, focusing on four separate but related areas.1. Strong-disorder quantum phase transitions: Motivated by experiments on nitrogen-vanadium, cerium-palladium-rhodium, and strontium-calcium ruthenate compounds, the PI aims to develop a theory of rare region effects at itinerant ferromagnetic quantum phase transitions. He will also study the influence of randomness on first-order quantum phase transitions as well as the effects of disorder correlations.2. Novel phases and transitions in layered systems: The PI will investigate the unusual phases and transitions emerging in randomly and quasi-periodically layered superconductors and superfluids that can be produced in ultracold gases or nano-structured materials.3. Dynamics and transport at quantum critical points: The PI will study the conductance of superconducting molybdenum germanium and niobium nanowires at the superconductor-metal quantum phase transition. He will also investigate electronic transport in ferromagnetic Griffiths phases.4 Berry phases in impurity problems and percolation transitions: The PI plans to analyze the effects of Berry phases on the quantum-to-classical mapping of impurity quantum phase transitions as well as their effects on percolation transitions of rotors and spins.A combination of analytical techniques and computer simulation will be used to carry out the research.This award also supports efforts to establish a series of "Nobel Prize talks" to be given each fall after the prizes in physics, chemistry and physiology or medicine have been announced. The talks in this series will be coordinated between the Missouri S&T departments of physics, chemistry and biological sciences. They will give elementary introductions into the science behind the prize. These talks will expand the successful series of talks on the physics prize that the PI has organized since 2007. The proposed work will also enhance the research and education infrastructure at Missouri S&T, as the Pegasus computer cluster designed and built and built by the PI becomes a hub of computational research in the Physics Department. NON- TECHNICAL SUMMARYThis award supports theoretical and computational research and education with the aim to advance understanding of a type of phase transition that occurs in materials at the absolute zero of temperature called a quantum phase transition. Unlike familiar phase transitions, for example the transformation of water to steam, which are driven by thermal fluctuations, quantum phase transitions are driven by quantum mechanical fluctuations, a consequence of the Heisenberg uncertainty principle. Quantum phase transitions are important because their influence can extend to temperatures, possibly as high as room temperature and beyond, and profoundly change the behavior of electrons in materials. This has consequences on the way electrons organize themselves into states of matter, such as magnetism and superconductivity, and other exotic states that have been predicted to occur in materials where electrons interact strongly with each other. The perhaps less familiar state of superconductivity has the unusual feature of being able to conduct electricity without losing energy to dissipation. This leads to potential applications in power transmission. Known superconducting materials only exhibit superconductivity at frigid temperatures, some as high as temperatures where atmospheric gases like oxygen and nitrogen are liquids. A better understanding of quantum critical phenomena may help discover materials that exhibit superconductivity at much higher temperatures. The rigorous description of quantum phase transitions lies outside the standard theory of phase transitions. This research has potential to open new areas in the study of phase transitions. Quantum phase transitions may also have important consequences for efforts to develop quantum computers which are based on the manipulation of quantum mechanical states, and nanoscale technologies involving elements that are some tens of thousands of times smaller than the diameter of a human hair.This award also supports efforts to establish a series of "Nobel Prize talks" to be given each fall after the prizes in physics, chemistry and physiology or medicine have been announced. The talks in this series will be coordinated between the Missouri S&T departments of physics, chemistry and biological sciences. They will give elementary introductions into the science behind the prize. These talks will expand the successful series of talks on the physics prize that the PI has organized since 2007. The proposed work will also enhance the research and education infrastructure at Missouri S&T, as the Pegasus computer cluster designed and built and built by the PI becomes a hub of computational research in the Physics Department.