Microscopic Theory of Quantum Fluids and Nuclear Systems

该奖项支持对广泛的量子多体问题的研究。主要目标是从第一性原理出发，预测具有基础和技术重要性的强相关系统的性质，假设实际的相互作用并处理密度和温度的实际条件。主要的焦点是在原子核和核物质的理论悬而未决的问题。然而，该研究也跨越了学科界限，涉及中子星物质、氦和其他量子液体、强相关电子系统、自旋晶格模型和格规系统等多体问题。大部分工作涉及到两种高度发展的半解析方法的应用，即自洽格林函数方法和相关基理论。除了它们的定量准确性和从头开始的特性外，这些方法还能够提供与量子相干性相关的重要系统特性的信息，这些信息还无法通过强力计算机模拟获得。在资助期间，将强调当前和长期关注的两个主题，即核系统中短期和长期相关性的对比作用以及在各种物理环境中量子相变的发生。在后一个主题中，配对现象正在用新技术进行研究，这些新技术有望对中子星的超流动性、外来核、液态氦-3以及高温超导性提供独特的见解。问题和目标的选择是由潜在的撞击设施和轨道天文台对紧凑天体物理物体的观测所驱动的。该项目的具体亮点包括(i)核物质和有限核中的电子远程激发的比较，以确定在核饱和特性的计算中是否应该排除这种相关性；（ii）对氧-16的集体特征的改进描述，将允许对单核子敲除的光谱因素和双核子去除的截面进行定量评估。(3)对实验数据进行分析，推断出原子核中最高动量质子（“最后缺失的质子”）的性质；(4)运用新的分析和计算方法，在配对理论中阐明中子物质、对称核物质、液态氦-3和量子色动力学的超流体相图；(5)探索费米-液体理论的分解；这体现在费米子凝聚和强相关系统中单粒子自由度的其他重排，以及（vi）与激光控制化学反应和量子计算相关的量子控制的数学和多体方面的研究。延续悠久的传统，为研究生在教学和研究方面的富有成效的职业生涯做准备，在该计划中发挥着核心作用，对其成功至关重要。

PHY-0140316ClarkThis award supports research on a broad spectrum of quantum many-body problems. The primary objective is prediction, from first principles,of the properties of strongly correlated systems of fundamental and technological importance, assuming realistic interactions and dealingwith realistic conditions of density and temperature. The main focus is on outstanding questions in the theory of nuclei and nuclear matter. However, the research also crosses disciplinary boundaries into many-body problems in neutron-star matter, helium and other quantum liquids, strongly correlated electron systems, spin-lattice models, and lattice-gauge systems. Much of the work involves application of two highly developed semi-analytic methods, namely the self-consistent Green's function approach and correlated-basis theory. In addition to their quantitative accuracy and ab initio character, these methods are capable of providing information on important system properties associated with quantum coherence that are not yet accessible to brute-force computer simulation. Two themes of current and enduring interest will be emphasized during the period of the grant, namely the contrasting roles of short- and long-range correlations in nuclear systems and the occurrence of quantum phase transitions in a rich variety of physical settings. Within the latter theme, pairing phenomena are being studied with new techniques that promise unique insights into superfluidity in neutron stars, exotic nuclei, and liquid Helium-3 as well as high-temperature superconductivity. The selection of problems and goals is motivated by the potential for impact facilities and observations of compact astrophysical objects from orbiting observatories. Specific highlights of the project include (i) a comparison of pionic long-range excitations in nuclear matter and in finite nuclei to determine whether such correlations should be excluded in the calculation of nuclear saturation properties, (ii) an improved description of collective features of Oxygen-16 that will permit quantitative evaluation of spectroscopic factors for single-nucleon knockout and cross sections for two-nucleon removal, (iii) analysis ofexperimental data to deduce the properties of the highest-momentum protons in the nucleus (the "last missing protons"), (iv) application of incisive new methods of analysis and computation in pairing theoryto elucidate the superfluid phase diagrams of neutron matter, symmetrical nuclear matter, liquid Helium-3, and quantum chromodynamics, (v)exploration of the breakdown of Fermi-liquid theory, as manifested in fermion condensation and other rearrangements of single-particle degrees of freedom in strongly correlated systems, and (vi) investigation of mathematical and many-body aspects of quantum control relevant to laser control of chemical reactions and to quantum computation. Continuing a long tradition, the preparation of graduate students for productive careers in teaching and research plays a central role in the program, essential to its success.