Quantum Phase Transitions of Correlated Electrons and Atoms

相关电子和原子的量子相变

• 批准号: 0757145
• 负责人: Subir Sachdev
• 金额: $ 43.5万
• 依托单位: Harvard University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2008
• 资助国家: 美国
• 起止时间: 2008-09-01 至 2011-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0757145&HistoricalAwards=false
• 关键词: Quantum; Phase; Transitions; Correlated; Electrons

TECHNICAL SUMMARY:This award supports theoretical research and education aiming to understand materials in the vicinity of quantum phase transitions. Quantum phase transitions occur across critical points where there is a qualitative change in the quantum mechanical ground state. By tuning parameters, such as carrier concentration, magnetic field strength, or pressure, new quantum phases with novel physical properties have been discovered. The PI aims to carry out a variety of theoretical studies motivated by remarkable experimental progress in Cu-based transition metal oxides, in organic compounds, in optical lattices of ultracold atoms, and in graphene. These examples include novel insulating spin gap states with evidence for valence bond solid order, one of which becomes a superconductor under applied pressure. The PI will study transitions between such phases which are metals, insulators, or superconductors. Many of these phases are characterized by exotic topological orders. The PI will study the response of such phases to impurities and other local perturbations, to make contact with nanoscale experimental probes such as the scanning tunneling microscope. The PI will also pursue investigations in the `quantum critical' region, found at intermediate temperatures near a quantum critical point, which has applications to observations in the underdoped cuprates, in thin superconducting films and wires, and in graphene. The PI has developed new tools to address quantum criticality by adapting advances in the string theory description of black holes. He plans to expand the reach of such tools to a wider class of strongly interacting many-body systems.This award supports activities beyond the research thrust, including connections with the global scientific community through visiting post-doctoral fellows, supported by fellowships from their home countries, the preparation of a more accessible second edition of the PI?s book ?Quantum Phase Transitions? which summarizes key ideas behind this research for graduate students.NON-TECHNICAL SUMMARY:This award supports theoretical research and education that aims to predict new states of matter and understand transformations among them and known states of matter. The research focuses on transformations that occur at the absolute zero of temperature in response to changes in a physical parameter such as pressure or the strength of interaction between electrons. Unlike more familiar transformations, like water to steam, these transformations of phase are not a consequence of changes in temperature. Rather they are a consequence of Heisenberg?s uncertainty principle, a cornerstone of quantum mechanics. These quantum phase transitions may be realized between new states of matter that may exist in high temperature superconductors, a class of organic conductors, systems of cold atoms trapped by light, and more. The PI?s work utilizes advanced theoretical techniques that benefit from ?cross-pollination? with branches of physics that study subatomic particles and the origins of gravity.This award supports activities beyond the research thrust, including connections with the global scientific community through visiting post-doctoral fellows, supported by fellowships from their home countries, the preparation of a more accessible second edition of the PI?s book ?Quantum Phase Transitions? which summarizes key ideas behind this research for graduate students.

技术摘要：该奖项支持理论研究和教育，旨在了解量子相过渡附近的材料。量子相变发生在量子机械基态发生质量变化的关键点上。通过调整参数，例如载体浓度，磁场强度或压力，已经发现了具有新型物理特性的新量子相。 PI的目的是进行各种理论研究，这些研究是由基于Cu的过渡金属氧化物，有机化合物，超电原子的光学晶格和石墨烯中的基于CU的过渡金属氧化物的显着实验进展所激发的。这些例子包括新的绝缘自旋隙状态，并具有价值键固体秩序的证据，其中之一在施加压力下变成了超导体。 PI将研究金属，绝缘体或超导体的这些阶段之间的过渡。这些阶段中的许多阶段的特征是外来拓扑顺序。 PI将研究此类阶段对杂质和其他局部扰动的反应，以与纳米级实验探针（例如扫描隧道显微镜）接触。 PI还将在量子临界点附近的中等温度下发现的“量子临界”区域进行研究，该区域在不含水层中的观测中应用，在薄的超导膜和电线中以及在石墨烯中。 PI开发了新的工具来通过调整黑洞的字符串理论描述中的进步来解决量子关键。他计划将此类工具的影响范围扩展到更广泛的强烈互动的多体系统。该奖项支持研究推力以外的活动，包括通过访问的博士后研究员与全球科学界的联系，并得到来自其本国的奖学金的支持，并准备了更易于获得的第二版PI？Quans s s Quantum sepritions？这是对研究生的这项研究背后的关键思想。没有技术摘要：该奖项支持理论研究和教育，旨在预测物质的新状态并了解它们之间以及已知的物质状态。 该研究的重点是响应物理参数（例如压力或电子之间的相互作用强度）的变化而在温度绝对零处发生的转换。与更熟悉的转化（如水到蒸汽）不同，这些相的转化并不是温度变化的结果。相反，它们是海森堡的不确定性原理的结果，这是量子力学的基石。可以在高温超导体中可能存在的新物质状态，一类有机导体，被光捕获的冷原子系统等之间实现这些量子相变。 PI的工作利用了受益于交叉授粉的高级理论技术？通过研究亚原子颗粒和重力的起源的物理学分支。该奖项支持研究推力以外的活动，包括通过访问的博士后研究员与全球科学界的联系，并在其本国的奖学金中支持，准备了更易于获取的第二版PI？Quantum Esperitions？这总结了研究生这项研究背后的关键思想。