Fractional Quantum Hall Physics with Ultracold Atoms

超冷原子的分数量子霍尔物理

• 批准号: 1506203
• 负责人: Markus Greiner
• 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: 2015
• 资助国家: 美国
• 起止时间: 2015-09-01 至 2018-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1506203&HistoricalAwards=false
• 关键词: Fractional; Quantum; Hall; Physics; Ultracold

This project is aimed at finding and exploring new states of matter, particularly "quantum matter" in which the counterintuitive and surprising effects of the theory of quantum mechanics plays a crucial role. In condensed matter materials such as conductors, superconductors, and magnets, atoms are arranged in regular crystals, and the electric and magnetic properties of the material emerge from the motion of electrons within that crystal. The physics of this motion is very complex, and many associated fundamental questions are unanswered. In order to better understand this physics, the scientists working on this project are building an enlarged model system of such matter: they are using atoms instead of electrons, and these atoms move in crystals formed by light. The atoms have to be at extremely cold temperatures, only a billionth of a degree above absolute zero. This way they behave quantum mechanically like the electrons in condensed matter systems. One strange feature of the ultracold system is that each atom is at many places at the same time. This synthetic condensed matter system can be very well characterized and directly compared to theory using a "Quantum Gas Microscope" (invented during the previous cycle of NSF funding to this research group) to image every single atom with perfect fidelity. The particular focus of this work is to create "Bosonic fractional quantum hall states"--states of matter whose behavior is dictated by "Entanglement," the most non-classical manifestation of quantum mechanics, famously described by Albert Einstein as "Spooky action in a distance." By addressing open questions linked to these materials, the researchers supported by this grant are working to advance science towards the ultimate goal of tailoring new quantum materials from scratch with yet unknown properties. Such materials could find applications in quantum information devices, and in quantum metrology. This project trains students and postdocs in a broad range of physics and in many modern technologies such as laser optics. Fractional quantum Hall states represent new states of matter that contain topological order. While Fermionic fractional quantum Hall states of electrons have been previously observed in 2D electron materials, the work supported by this grant work aims to experimentally realize and explore fractional quantum Hall states with small ensembles of strongly interacting bosonic atoms that quickly rotate in a two-dimensional harmonic trap. Such ensembles experience a gauge field, and are expected to adiabatically transition into the bosonic fractional quantum Hall state. While the particle number in such ensembles is small, on the order of 4-10 particles, the quantum gas microscope will enable the researchers to detect every single particle with near unity fidelity. Therefore, they can carry out a complete quantum limited measurement of the mesoscopic many- body system. In particular they seek to directly measure particle correlation functions in momentum space, which would give very direct evidence of the highly entangled many-body states.

该项目旨在查找和探索物质的新状态，尤其是“量子物质”，其中量子力学理论的违反直觉和令人惊讶的影响起着至关重要的作用。在凝聚的物质材料（例如导体，超导体和磁铁）中，原子在常规晶体中排列，并且该材料的电和磁性来自该晶体内电子的运动。这项运动的物理学非常复杂，许多相关的基本问题没有解决。为了更好地理解这种物理，从事该项目的科学家正在建立一个这样的问题的模型系统：它们使用原子而不是电子，这些原子以光形成的晶体移动。原子必须处于极度冷的温度下，仅超过绝对零的十亿度。这样，它们像冷凝物质系统中的电子一样机械地行为。 超低系统的一个奇怪特征是，每个原子在许多地方都同时是。使用“量子气体显微镜”（在NSF资金向该研究组的上一个量子循环中发明的量子显微镜），可以很好地表征这种合成的冷凝物质系统，并直接与理论进行比较，以形象以完美的保真度对每个原子进行图像。这项工作的特殊重点是创建“玻色粒分数量子厅态”，即行为由“纠缠”决定的物质状态，这是量子力学的最不经典的表现，由艾尔伯特·爱因斯坦（Albert Einstein）著名地描述为“远处的怪异作用”。通过解决与这些材料相关的开放问题，这笔赠款支持的研究人员正在努力促进科学朝着从头开始量身定制新的量子材料的最终目标。此类材料可以在量子信息设备和量子计量学中找到应用。该项目在广泛的物理学和许多现代技术（例如激光光学）中培训学生和博士后。分数量子厅状态代表包含拓扑顺序的物质的新状态。虽然先前已经在2D电子材料中观察到了电子量子大厅的典型分数量子大厅状态，但该赠款工作支持的工作旨在实验实现并探索具有很小相互作用的玻色原子的小集合的分数量子霍尔状态，这些剂量很大，这些剂量是牢固相互作用的剂量原子，这些剂量在二维谐波中迅速旋转。这样的合奏经历了量规场，并有望绝热地过渡到玻色子分数量子厅状态。尽管此类合奏中的粒子数很小，但按照4-10个颗粒的顺序，量子气体显微镜将使研究人员能够以几乎统一的保真度检测每个粒子。因此，他们可以对介质多体系统进行完整的量子限制测量。特别是他们试图直接测量动量空间中的粒子相关函数，这将提供非常直接的证据证明高度纠缠的多体状态。