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.

当前科学和技术感兴趣的许多材料的新物理性质源自由于电子动能和势能之间的竞争而产生的强相关性。在操纵光学晶格中捕获的超冷原子的动能和相互作用的能力方面的进展导致了使用冷原子来模拟其他系统（如相关量子材料）的想法。激发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强相关量子系统中观察到的新兴宏观行为。在未来五年的研究计划中，我打算采取的方法是：i）发展和完善具有广泛适用性的理论技术; ii）从理论上研究特定的冷原子系统和强关联电子材料。我打算重点关注的具体项目是：a）最近发现的一类稀磁半导体（DMS）中的铁磁性，B）有机电荷转移盐中的电荷涨落效应，c）光学晶格中冷玻色子的平衡动力学，d）冷原子的人工磁场和电场。 对强关联电子材料的兴趣可能来自潜在的应用或不寻常的物理性质。我所提出的研究包含了这两种观点。I）今年发现了一类新的具有相对高居里温度的DMS。这提供了一个发展理论来解释铁磁性的机会，这可能有助于这类材料未来自旋电子应用的发展。II）有机电荷转移盐是一类有吸引力的材料，在其中研究强相关性，因为它们表现出丰富的现象，如非常规超导性，自旋液体和弛豫铁电行为。我将研究这些系统中电荷涨落效应在影响相关量子态中的作用。 冷原子系统具有真实的可调参数的能力，这使得它成为研究量子多体系统失平衡动力学的一个非常有吸引力的背景。我最近开发了一种形式主义来描述玻色哈伯德模型中的物理学，该模型描述了光学晶格中的冷玻色子。对于不同的量子淬火协议（量子临界点的动态遍历），最终状态可能是热化的，像玻璃一样冻结，或者具有缺陷的增殖。我将计算量子猝灭期间和之后的空间和时间发展，以给出一个微观图像，连接到最先进的实验，在单原子水平的图像。冷原子是电中性的，因此不直接与电磁场耦合。人造磁场和电场已经产生，它们模仿物理场，但比实验室中可实现的强得多。我将研究这些场在平衡状态和非平衡状态下可能产生的新现象。 这项工作的结果将对自旋电子学，强关联电子和超冷原子领域的研究人员产生重大兴趣。更广泛地说，这项工作将有助于在加拿大国内外推动这些领域的努力，其好处将通过采用新材料或量子模拟的未来技术惠及加拿大人。该提案还将为年轻研究人员提供高质量的凝聚态理论培训。