Geometric Frustration in an Optical Superlattice

光学超晶格中的几何挫败

• 批准号: 1206093
• 负责人: Dan Stamper-Kurn
• 金额: $ 54万
• 依托单位: University of California-Berkeley
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2012
• 资助国家: 美国
• 起止时间: 2012-09-01 至 2015-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1206093&HistoricalAwards=false
• 关键词: Geometric; Frustration; Optical; Superlattice

The structure of many materials is determined by how the constituents of the material obey the many constraints that are established by microscopic physical principles. For example, stable crystalline structures are those that are constrained to minimize the pairwise interactions between the atoms or molecules forming the crystal. Similarly, in magnetic materials, the magnetic moments of electrons that are localized on neighboring atoms may lower their energy either by aligning in the same or in opposite orientations. In some cases, there is no trivial way in which to satisfy all the energetic constraints within a system, and so the formation of any simple configuration of the system -- e.g. of magnetic moments within a crystalline structure -- is precluded. This phenomenon is known as frustration. The question of whether some sort of predictable order is established in frustrated systems, and, if so, what is the character of that order, are both major open questions in physics. The answer to these questions has relevance to the design of new materials and the application of such materials to information technology and other uses.In this project, the physics of frustrated materials will be explored using cold atoms that are trapped within geometric patterns -- such as the two-dimensional kagome lattice -- that lead to a high degree of frustration. The effects of this frustration on phase transitions and on transport will be investigated. The system chosen provides a clean realization of geometric frustration, free of the structural defects that influence solid-state realizations of similar systems. Thus, the experimental findings may provide clear answers to vexing questions regarding geometric frustration.

许多材料的结构取决于材料的成分如何遵守微观物理原理所建立的许多约束。 例如，稳定的晶体结构是那些被限制为最小化形成晶体的原子或分子之间的成对相互作用的结构。 类似地，在磁性材料中，位于相邻原子上的电子的磁矩可以通过以相同或相反的方向排列来降低其能量。 在某些情况下，没有简单的方法可以满足系统内的所有能量约束，因此形成系统的任何简单配置 - 例如晶体结构内的磁矩——被排除。 这种现象被称为挫败感。 在受挫系统中是否建立了某种可预测的秩序，如果是的话，该秩序的特征是什么，这两个问题都是物理学中的主要开放问题。 这些问题的答案与新材料的设计以及此类材料在信息技术和其他用途中的应用有关。在这个项目中，将使用被困在几何图案中的冷原子来探索受阻材料的物理特性——例如就像二维戈薇晶格——这会导致高度的挫败感。 将研究这种挫折对相变和运输的影响。 所选择的系统提供了几何挫折的清晰实现，没有影响类似系统的固态实现的结构缺陷。 因此，实验结果可能为有关几何挫败的棘手问题提供明确的答案。