Disorder Effects in Ultracold Atomic Physics

超冷原子物理学中的无序效应

• 批准号: 1068159
• 负责人: Mark Havey
• 金额: $ 42.9万
• 依托单位: Old Dominion University Research Foundation
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2011
• 资助国家: 美国
• 起止时间: 2011-09-01 至 2015-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1068159&HistoricalAwards=false
• 关键词: Disorder; Effects; Ultracold; Atomic; Physics

The scientific research in this project is directed towards the interface between atomic and condensed matter physics. A particular focus is quantum optics in high-density and ultra cold atomic gases, in which disorder-driven electromagnetic interactions can develop strongly correlated character, typified by Anderson localization of light and the onset of random lasing. The overriding theme of the research program is investigation of the physics of strongly correlated atomic-radiative systems, including phase transitions in ultracold atomic vapor. A closely related secondary theme appears when such systems are electromagnetically dressed by an external field. Then new phenomena, including formation of a diffusive dark state quasiparticle, are expected to emerge. This fundamental research project focuses on manifestations of localization of electromagnetic waves in ultracold gases. As individual photons are noninteracting bosons, a nearly idealized system can be realized with a spatially disordered gas of atomic scatterers. Measurement of the time evolution of light emerging from a sufficiently dense sample provides strong measures of the development of localized states. These include a departure from diffusive light transport at a characteristic localization time, the temporal evolution of the light intensity for times larger than the localization time, and the appearance of critical fluctuations in the vicinity of the localization transition. These quantities are analyzed by time-dependent models of localization, and by atomic models of light localization, to obtain critical exponents and parameters characterizing the localization transition. The role of interactions among the scatterers, as induced by the localized field itself, forms an essential focus area of the research. A second general area, coherent control of weak light localization, is also being pursued. In these studies, a spatially disordered atomic gas is dressed with a strong control field, modifying the localization of a multiply scattered, weak probe beam. Among other applications, this serves as a measure of the fidelity of single photon storage and retrieval, and can have an important impact on an array of problems in quantum linear and nonlinear optics and quantum information. Overall, this research project has significant potential scientific and technical impact in a wide range of basic and practical areas, these associated with the inevitable presence of disorder in realistic systems. These include quantum phase transitions, deeper understanding of the role of gain and the development of random lasing in disordered systems, and new mechanisms for quantum light storage in quantum information science. Beyond these more technical aspects, the research program also has significant impact on science education, infrastructure, and diversity. This is partly accomplished by substantially involving undergraduate and graduate students in all parts of the research projects, including attendance at undergraduate-focused symposia at professional conferences. Students participate in undergraduate (independent study and Senior Thesis research) and M.S. Thesis study associated with the experiments. In the past decade, 14 Ph.D. and many M.S. students, nearly half of whom are women, have been involved in our research projects. Through active recruitment of talented undergraduates, paid internships, and our previous track record, we expect that pattern to continue. Most graduated students have gone on to technical industrial positions, while the remainder are involved in science education at all levels. Finally, the research impacts international science education and infrastructure through involvement of Ph.D. students and faculty in international components of this research with academic colleagues and students in Russia and France.

本项目的科学研究方向是原子和凝聚态物理之间的界面。特别关注的是高密度和超冷原子气体中的量子光学，其中无序驱动的电磁相互作用可以发展出强相关特征，以光的安德森局域化和随机激光的开始为典型。研究计划的首要主题是研究强相关原子辐射系统的物理学，包括超冷原子蒸汽中的相变。当这样的系统被外部磁场电磁包裹时，一个密切相关的次要主题就会出现。然后，新的现象，包括扩散暗态准粒子的形成，有望出现。本基础研究项目主要研究电磁波在超冷气体中的局域化表现。由于单个光子是不相互作用的玻色子，因此可以用空间无序的原子散射体气体来实现近乎理想的系统。测量从足够稠密的样品中发出的光的时间演化提供了局域状态发展的有力测量。这些变化包括在一个特征的局部化时间偏离漫射光输运，光强的时间演变比局部化时间大几倍，以及在局部化转变附近出现临界波动。这些量通过依赖时间的局域化模型和光局域化的原子模型进行分析，以获得表征局域化跃迁的关键指数和参数。局域场本身引起的散射体之间相互作用的作用是研究的一个重要焦点。第二个一般领域，弱光定位的相干控制，也正在研究中。在这些研究中，一个空间无序的原子气体被一个强大的控制场，改变了多散射，弱探测光束的定位。在其他应用中，这可以作为单光子存储和检索保真度的度量，并且可以对量子线性和非线性光学以及量子信息中的一系列问题产生重要影响。总体而言，该研究项目在广泛的基础和实践领域具有重要的潜在科学和技术影响，这些领域与现实系统中不可避免的无序存在有关。这些包括量子相变，对增益作用的更深入理解和无序系统中随机激光的发展，以及量子信息科学中量子光存储的新机制。除了这些更技术性的方面，该研究项目还对科学教育、基础设施和多样性产生了重大影响。这部分是通过让本科生和研究生大量参与研究项目的所有部分来实现的，包括参加专业会议上以本科生为重点的专题讨论会。学生参加与实验相关的本科（独立学习和高级论文研究）和硕士论文研究。在过去的十年中，有14位博士和许多硕士学生参与了我们的研究项目，其中近一半是女性。通过积极招聘有才华的本科生，带薪实习，以及我们以往的记录，我们预计这种模式将继续下去。大多数毕业的学生都进入了技术工业岗位，而其余的人则参与了各级科学教育。最后，通过博士生和教师与俄罗斯和法国的学术同事和学生参与这项研究的国际组成部分，该研究影响了国际科学教育和基础设施。