Topics in Statistical Physics

凝聚态系统中与淬灭随机性和输运相关的集体现象将被研究。要研究的现象包括热波动和钉住对ii型超导体在磁场中的平衡和非平衡行为的影响，以及自旋玻璃、随机磁铁和其他系统（如交联凝胶）的静力学和动力学。所有这些都涉及到存在随机性和慢动力学的经典相变，这是由势垒高度分布引起的。非线性集体输运现象的统计行为，如超导体中通量线的非线性动力学、滑动电荷密度波、多孔介质中的流体、砂堆和地质断层的运动等，将重点研究它们的普遍特征。随机性对超流体、超导体、金属和自旋系统的低温量子力学行为的影响也将被研究。特别是，零温度相变的性质，如金属-绝缘体相变，将被研究。对多粒子系统的集体行为的研究是凝聚态或固态物理学的基础。然而，这些系统很少是完美的。在不同程度上，所有凝聚态系统都具有与其性质相关的随机性。拟议的研究将研究当前感兴趣的各种特定系统（如超导体和磁体）中随机性的影响，以确定其对系统静力学，动力学和输运的影响。这项基础研究将寻找这些系统共有的普遍特征，从而为各种凝聚态系统的行为提供坚实的物理理解。

Collective phenomena in condensed matter systems associated with quenched randomness and transport will be investigated. Phenomena to be studied include the effects of thermal fluctuations and pinning on eqilibrium and non-equilibrium behavior in Type-II superconductors in a magnetic field and statics and dynamics of spin glasses, random magnets and other systems such as cross-linked gels. All of these involve classical phase transitions in the presence of randomness and slow dynamics which result from a distribution of barrier heights. The statistical behavior of nonlinear collective transport phenomena such as the nonlinear dynamics of flux lines in superconductors, sliding charge density waves, fluids in porous media, sand piles and the motion of geologic faults will be studied with an emphasis on their universal features. The effects of randomness on low temperature quantum mechanical behavior of superfluids, superconductors, metals and spin systems will also be investigated. In particular, the nature of the zero temperature phase transitions, such as metal-insulator transitions, will be studied. %%% The study of the collective behavior of many-particle systems lies at the foundation of condensed matter, or solid state, physics. However, very few, if any, of these systems are perfect. To varying degrees all condensed matter systems have randomness associated with their properties. The proposed research will study the effects of randomness in a variety of specific systems of current interest, such as superconductors and magnets, to determine its effects on the system statics, dynamics and transport. This basic research will look for universal features which are common to these systems and thus provide a solid physical understanding of the behavior of a variety of condensed matter systems.