论文标题
在无序自旋链中定位的动态阻塞
Dynamical obstruction to localization in a disordered spin chain
论文作者
论文摘要
我们分析了无序磁场中的一维XXZ自旋链。作为系统行为的主要探针，我们使用特征态对绝热转化的敏感性，如通过忠诚度敏感性表达，以及光谱函数的低频渐近线。我们确定了一个最大混乱区域（具有指数增强的敏感性），该区域将多体性局部相位与扩散的梯形相分开。该机制的特征是缓慢运输，我们认为这种缓慢动力学的存在与热力学极限中的定位过渡不相容。该系统似乎没有定位，而是以中等障碍值的值进入通用的副定义弛豫状态，其中局部纵向磁化的光谱函数与频率成反比，与对数的自动相关功能相对应。
We analyze a one-dimensional XXZ spin chain in a disordered magnetic field. As the main probes of the system's behavior we use the sensitivity of eigenstates to adiabatic transformations, as expressed through the fidelity susceptibility, in conjunction with the low frequency asymptotes of the spectral function. We identify a region of maximal chaos -- with exponentially enhanced susceptibility -- which separates the many-body localized phase from the diffusive ergodic phase. This regime is characterized by slow transport and we argue that the presence of such slow dynamics is incompatible with the localization transition in the thermodynamic limit. Instead of localizing, the system appears to enter a universal subdiffusive relaxation regime at moderate values of disorder, where the spectral function of the local longitudinal magnetization is inversely proportional to the frequency, corresponding to logarithmic in time relaxation of its auto-correlation function.
