Microscopic Theory of Quantum Fluids and Nuclear Systems

PHY-0140316Clark该奖项支持对广泛的量子多体问题的研究。主要目标是从第一原理出发，假设现实的相互作用，并处理密度和温度的现实条件，预测具有基础和技术重要性的强关联系统的性质。主要焦点是原子核和核物质理论中的悬而未决的问题。然而，这项研究也跨越了学科界限，进入了中子星物质、氦和其他量子液体、强关联电子系统、自旋-晶格模型和晶格-规范系统的多体问题。许多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算特性之外，这些方法还能够提供与量子相干相关的重要系统属性的信息，这些属性还无法通过暴力计算机模拟获得。在赠款期间，将强调当前和持久感兴趣的两个主题，即核系统中短期和长期关联的不同作用以及在丰富的各种物理环境中发生的量子相变。在后一个主题中，配对现象正在用新的技术进行研究，这些技术有望对中子星、奇异核、液态氦-3以及高温超导中的超流性提供独特的见解。选择问题和目标的动机是考虑到撞击设施的可能性和轨道天文台对致密天体物理物体的观测。该项目的具体亮点包括：(I)比较核物质和有限核中的轻子长程激发，以确定这种关联是否应被排除在核饱和性质的计算中；(Ii)改进对氧-16集体特征的描述，这将允许对单核子敲除的光谱因子和两核子去除的截面进行定量评估；(Iii)分析实验数据，以推断核中最高动量质子的性质(“最后丢失的质子”)；(Iv)在配对理论中应用新的分析和计算方法来阐明中子物质的超流相图，对称核物质、液态氦-3和量子色动力学，(V)探索费米-液体理论的崩溃，表现为费米子凝聚和强关联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有关的量子控制的数学和多体方面的研究。延续了悠久的传统，为研究生在教学和研究领域从事富有成效的职业生涯做好准备在该项目中发挥着核心作用，这对项目的成功至关重要。

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.