低维关联量子系统的非平衡超快动力学过程研究

项目名称： 低维关联量子系统的非平衡超快动力学过程研究

项目编号： No.11474136

项目类型： 面上项目

立项/批准年度： 2015

项目学科： 数理科学和化学

项目作者： 陆汉涛

作者单位： 兰州大学

项目金额： 80万元

中文摘要： 近年来，亚皮秒分辨率下的光学探测和实验手段为凝聚态物理中关联材料的研究提供了新的强有力的工具，因为在小于系统弛豫和退相干特征时间的时间分辨率下获得的信息可以为人们提供关于系统内部自由度的大量细节。在这一时间尺度下发现了许多新的实验现象，例如光致诱导相变。这些实验进展对理论提出了挑战，要求能够对关联材料的超快非平衡演化进行有效的计算模拟和预言，而其所面临的核心困难是对关联量子涨落和非平衡的处理。本项目以大规模数值模拟为主要手段对低维量子关联系统的非平衡超快动力学过程进行研究。方法上，我们进一步发展含时精确对角化和密度矩阵重整化群，使其能够准确计算多自由度耦合的低维系统在实验相关的时间尺度下的动力学行为。从物理上，我们研究在超快外场激励下，多体系统非平衡演化的微观过程和机理。通过数值结果与实验的比较，逐步建立起模型计算和实验的直接联系，并探讨由于关联效应可能导致的新奇非平衡量子现象。

中文关键词： 关联体系；超快过程；非平衡系统；光致诱导现象

英文摘要： Recently, in the condensed matter physics community, sub-picosecond measurements have been proven to be a powerful and state-of-the-art?tool to study correlated materials. In such high time resolutions, which are typically less than the characteristic relaxation and dephasing time scales of the systems under studies, plenty of details of the degrees of freedom inside the systems can be reached. In consequence, not much surprisingly, many interesting phenomena have emerged, such as photoinduced phase transitions. The progress in experiments creates demands for theory to obtain the capacity to calculate efficiently the ultrafast nonequilibrium processes in correlated materials and to make relevant predictions. The challenge lies in the dual hardness of quantum fluctuations due to strong correlations and nonequilibrium. To address the issue, this project employs large-scale numerical simulations as main tools, to investigate the ultrafast nonequilibrium processes of low-dimensional correlated systems. In terms of numerical methods, we further develop and improve the time-dependent exact diagonalization and density-matrix renormalization group, in order to describe efficiently the systems' dynamics in time scales relevant to experiments. In physics, we aim in this way to look into the mechanisms of nonequilibrium phenomena of many-body systems when they are subjected to ultrafast stimuli.The final goal of the project is to establish the bridge step-by-step connecting model simulations to on-going experiments in this area, as well as to unearth novel nonequilibrium quantum phenomena originated from correlation effects.

英文关键词： correlated systems;ultrafast process;nonequilibrium;photoinduced phenomena