Disorder Effects in Ultracold Atomic Physics

该项目的科学研究方向是原子物理和凝聚态物理之间的接口。 一个特别的焦点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的特征，典型的是光的安德森局域化和随机激光的发生。 该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，包括超冷原子蒸气中的相变。一个密切相关的次要主题出现时，这样的系统是由一个外部场电磁打扮。然后，新的现象，包括形成一个扩散的暗态准粒子，预计将出现。 这个基础研究项目的重点是超冷气体中电磁波局部化的表现。 由于单个光子是不相互作用的玻色子，所以可以用空间无序的原子散射体气体来实现一个近乎理想化的系统。从足够密集的样品中出现的光的时间演化的测量提供了局域态的发展的强有力的措施。 这些包括偏离漫射光传输在一个特征的本地化时间，时间演化的光强度大于本地化时间，和本地化过渡附近的临界波动的外观。 这些量的分析与时间相关的本地化模型，并通过原子模型的光本地化，以获得临界指数和参数的本地化过渡的特点。 由局域场本身引起的散射体之间的相互作用的作用形成了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，也正在进行中。 在这些研究中，一个空间无序的原子气体是穿着一个强大的控制领域，修改本地化的多重散射，弱探测光束。 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。 总的来说，这个研究项目在广泛的基础和实践领域具有重大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混乱有关。 其中包括量子相变，更深入地理解增益的作用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。 除了这些技术方面，研究计划还对科学教育，基础设施和多样性产生了重大影响。这部分是通过大量涉及本科生和研究生在研究项目的各个部分，包括在专业会议本科生为重点的研讨会出席完成。学生参加本科（独立学习和高级论文研究）和硕士。论文研究与实验相结合。 在过去的十年里，14个博士。许多MS学生，其中近一半是妇女，参与了我们的研究项目。 通过积极招聘有才华的本科生，带薪实习，以及我们以前的业绩记录，我们预计这种模式将继续下去。 大多数毕业生已进入工业技术岗位，而其余的则参与各级科学教育。最后，研究通过博士的参与影响国际科学教育和基础设施。学生和教师在这项研究的国际组成部分与学术同事和学生在俄罗斯和法国。

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.