Novel Phases of Quantum Matter

量子物质的新相

• 批准号: 1103860
• 负责人: Subir Sachdev
• 金额: $ 45万
• 依托单位: Harvard 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: 2011-09-01 至 2014-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1103860&HistoricalAwards=false
• 关键词: Novel; Phases; Quantum; Matter

TECHNICAL SUMMARYThis award supports theoretical research and education to explore the properties of strongly interacting quantum matter, as realized in a wide variety of transition metal compounds, and in systems of trapped ultra-cold atoms. Special attention will be paid to layered compounds with antiferromagnetism and higher temperature superconductivity: examples are the cuprates, the pnictide compounds, the Bechgaard salts, and rare-earth heavy-fermion compounds. The PI has proposed a common phase diagram which has successfully described the variation in physical properties as a function of temperature, applied magnetic field, and a tuning parameter like electron density or pressure, across these comprehensive series of materials. Central actors in this phase diagram are quantum phase transitions, involving the onset of spin magnetism and other orders, in metals and superconductors. The PI has described the strong-coupling structure of the theory of such transitions in two spatial dimensions, and proposed to develop the theory to produce new experimental tests of our understanding. The theory also allows for more exotic intermediate phases, with subtle types of quantum entanglement or 'topological order;' the PI will study their features while making contact with experimental studies on certain organic insulators. The theories of strong quantum correlations will also be applied to experiments on trapped ultra-cold atoms, and to electron spin physics in graphene. Finally, there are also remarkable connections between the possible phases of strongly interacting quantum matter, and the states of gravitational theories in anti-de Sitter space, through a gauge-gravity duality. The PI will continue his research at this interface area.This award also supports education at the graduate and postdoctoral level, as well as outreach to the public and the preparation of the next edition of an authoritative textbook in the field. NONTECHNICAL SUMMARYThis award supports theoretical research and education with the aim to explore quantum matter. Quantum matter is formed when large numbers of interacting particles are at temperatures low enough so that the concepts of quantum mechanics play a crucial role in determining its distinguishing characteristics. For electrons in solids, the needed 'low' temperatures can be even higher than room temperature. For gases of trapped atoms, ultra-cold temperatures about one billionth of a degree from the absolute zero of temperature are needed. Remarkably, a common set of ideas has found application across this wide range of energy scales. Some of the most interesting phases of quantum matter are associated with the interplay between magnetism and superconductivity. Electrons may be thought of as tiny magnets and magnetism arises from the co-operative arrangement of the magnetic axes of the electrons. Superconductivity is the ability of pairs of electrons to carry electrical current without dissipation. The PI will study how by varying material parameters, it is possible to drive a system of electrons from a magnetic to a superconducting state, across a variety of 'quantum phase transitions.' Such phase transitions are analogous to familiar thermal transitions, like water changing to steam, but are associated here with subtle quantum correlations between the electrons. Concepts from the theory of quantum phase transitions inform our understanding of the measureable properties of quantum matter in the laboratory.The PI will also explore emerging connections between the theory of quantum matter, and seemingly unrelated work on the quantum theory of black hole horizons. These fields share a common interest in how many particles can become 'entangled' with each other quantum mechanically across large distances; their distinct approaches to entanglement have led to mutually beneficial insights.This award also supports education at the graduate and postdoctoral level, as well as outreach to the public and the preparation of the next edition of an authoritative textbook in the field.

该奖项支持理论研究和教育，以探索强相互作用量子物质的性质，如在各种过渡金属化合物和被困超冷原子系统中实现的。特别注意的是具有反铁磁性和高温超导性的层状化合物：例如铜酸盐、磷属元素化合物、贝奇加德盐和稀土重费米子化合物。PI提出了一个通用的相图，它成功地描述了这些综合系列材料中物理性质随温度、外加磁场和电子密度或压力等调谐参数的变化。在这个相图中的中心角色是量子相变，涉及金属和超导体中自旋磁性和其他秩序的开始。PI已经描述了这种跃迁理论在两个空间维度上的强耦合结构，并建议发展该理论以产生我们理解的新实验测试。该理论还允许更奇异的中间相，具有微妙的量子纠缠或“拓扑顺序”; PI将研究它们的特征，同时与某些有机绝缘体的实验研究联系起来。强量子关联理论也将应用于被困超冷原子的实验，以及石墨烯中的电子自旋物理。最后，强相互作用量子物质的可能相与反德西特空间中的引力理论态之间，通过规范-引力对偶性，也存在着显著的联系。PI将继续在这一领域进行研究。该奖项还支持研究生和博士后水平的教育，以及向公众宣传和编写该领域权威教科书的下一版。该奖项支持理论研究和教育，旨在探索量子物质。当大量相互作用的粒子处于足够低的温度时，量子物质就形成了，因此量子力学的概念在确定其区别特征方面发挥了至关重要的作用。对于固体中的电子，所需的“低”温度甚至可以高于室温。对于被捕获的原子气体，需要离绝对零度十亿分之一度的超冷温度。值得注意的是，一套共同的想法已经在这种广泛的能量尺度上得到了应用。量子物质的一些最有趣的相与磁性和超导性之间的相互作用有关。电子可以被认为是微小的磁铁，磁性来自于电子磁轴的协同排列。超导性是电子对携带电流而不耗散的能力。PI将研究如何通过改变材料参数，将电子系统从磁性状态驱动到超导状态，跨越各种量子相变。“这种相变类似于熟悉的热转变，比如水变成蒸汽，但这里与电子之间的微妙量子相关性有关。量子相变理论的概念告诉我们量子物质在实验室中的可测量性质的理解。PI还将探索量子物质理论之间的新兴联系，以及黑洞视界量子理论上看似无关的工作。这些领域都对有多少粒子可以在大距离上以量子力学的方式相互“纠缠”有着共同的兴趣;他们独特的纠缠方法带来了互利的见解。该奖项还支持研究生和博士后水平的教育，以及向公众宣传和编写该领域权威教科书的下一版。