Strong correlations of atoms in optical lattices and electrons in quantum materials

光学晶格中的原子与量子材料中的电子的强相关性

• 批准号: RGPIN-2014-06474
• 负责人: Kennett, Malcolm
• 金额: $ 1.38万
• 依托单位: Simon Fraser University
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2016
• 资助国家: 加拿大
• 起止时间: 2016-01-01 至 2017-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=612245
• 关键词: Strong; correlations; atoms; optical; lattices

The novel physical properties of many materials of current scientific and technological interest derive from the strong correlations that arise due to competition between electron kinetic and potential energy. Advances in the ability to manipulate kinetic energy and interactions in ultra-cold atoms trapped in optical lattices have led to the idea of using cold atoms to simulate other systems such as correlated quantum materials. The scientific challenge that motivates my research program is to develop theory to understand how the interplay of microscopic degrees of freedom leads to observed emergent macroscopic behaviour in strongly correlated quantum systems. The approaches I intend to take in my research program in the next five years are i) to develop and refine theoretical techniques with wide applicability and ii) to investigate specific cold atom systems and strongly correlated electron materials theoretically. Particular projects I intend to focus on are a) ferromagnetism in a very recently discovered class of diluted magnetic semiconductors (DMSs), b) charge fluctuation effects in organic charge transfer salts, c) out of equilibrium dynamics for cold bosons in optical lattices and d) artificial magnetic and electric fields for cold atoms. Interest in particular strongly correlated electron materials may come from potential applications or unusual physical properties. My proposed research encompasses both points of view. I) This year a new class of DMSs with a relatively high Curie temperature has been discovered. This presents an opportunity to develop theory to explain the ferromagnetism which may assist the development of future spintronic applications of this class of materials. II) Organic charge transfer salts are an attractive class of materials in which to study strong correlations as they exhibit a rich range of phenomena such as unconventional superconductivity, spin liquid and relaxor ferroelectric behaviour. I will investigate the role of charge fluctuation effects in these systems in affecting correlated quantum states. The ability to tune the parameters in cold atom systems in real time makes them a very attractive setting to study the challenging problem of the out of equilibrium dynamics of interacting quantum many-body systems. I recently developed a formalism to describe this physics in the Bose Hubbard model, which describes cold bosons in an optical lattice. For different quantum quench protocols (a dynamic traversal of a quantum critical point) the final state may be thermalized, frozen like a glass, or have a proliferation of defects. I will calculate spatial and temporal development of order during and after a quantum quench to give a microscopic picture to connect to state-of-the-art experiments which image at the single atom level. Cold atoms are electrically neutral and hence do not couple to electromagnetic fields directly. Artificial magnetic and electric fields have been generated which mimic physical fields but can be much stronger than those achievable in the laboratory. I will study novel phenomena that can arise from such fields both in and out of equilibrium. The results of this work will be of significant interest to researchers working in the areas of spintronics, strongly correlated electrons and ultra cold atoms. More broadly, this work will contribute to efforts to advance these fields both in and outside Canada, the benefits of which will reach Canadians through future technologies incorporating novel materials or quantum simulation. This proposal will also provide high quality training in condensed matter theory for young researchers.

当前科学和技术兴趣的许多材料的新型物理特性源于由于电子动力学和势能之间的竞争而引起的强相关性。操纵动能的能力和被困在光学晶格中的超冷原子中的相互作用的能力的进步导致了使用冷原子模拟其他系统（例如相关量子材料）的想法。激励我的研究计划的科学挑战是发展理论，以了解微观自由度的相互作用如何导致在密切相关的量子系统中观察到的新兴宏观行为。我打算在未来五年内打算采用的研究计划是我）开发和完善具有广泛适用性的理论技术，ii）研究特定的冷原子系统并从理论上讲非常相关的电子材料。我打算关注的特定项目是a）在最近发现的一类稀释的磁性半导体（DMS）中，b）有机电荷转移盐中的电荷波动效应，c）来自光学玻璃体的平衡动力学的光学动力学和D。 ）冷原子的人造磁场和电场。 特别相关的电子材料的兴趣可能来自潜在的应用或异常的物理特性。我提出的研究涵盖了这两个观点。 i）今年已经发现了一类新的DMS，居中温度相对较高。这为开发理论提供了解释铁磁性的机会，这可能有助于开发此类材料的未来自旋应用。 ii）有机电荷转移盐是一种有吸引力的材料类别，可以在其中研究强相关性，因为它们表现出丰富的现象范围，例如非常规超导性，自旋液体和宽松的铁电行为。我将研究电荷波动效应在这些系统影响相关量子状态中的作用。 实时调整冷原子系统中参数的能力使它们成为一个非常有吸引力的环境，可以研究相互作用的量子多体系统的均衡动力学的具有挑战性的问题。我最近开发了一种形式主义，以在Bose Hubbard模型中描述这种物理学，该模型描述了光学晶格中的冷玻色子。对于不同的量子淬灭协议（量子临界点的动态遍历），最终状态可以被热化，像玻璃一样冷冻，或者具有缺陷的扩散。我将计算量子淬灭期间和之后的秩序的空间和时间开发，以给出微观图片，以连接到最新的实验，这些实验在单个原子水平上图像。冷原子是电中性的，因此不会直接落到电磁场。已经生成了模仿物理场的人造磁场和电场，但可能比实验室可实现的磁场强得多。我将研究可能由均衡的此类领域引起的新现象。 这项工作的结果将引起研究人员在旋转，非常相关的电子和超冷原子领域的研究人员的重大兴趣。更广泛地说，这项工作将有助于努力推进加拿大内外的这些领域，其好处将通过结合新型材料或量子模拟的未来技术来吸引加拿大人。该建议还将为年轻研究人员提供凝结物质理论的高质量培训。