Department of Physics, The Pennsylvania State University, University Park, PA 16802, United States of America.
Department of Electrical and Computer Engineering, Princeton University, Princeton, NJ 08544, United States of America.
Rep Prog Phys. 2023 Feb 2;86(3). doi: 10.1088/1361-6633/acb36e.
Many experimentally relevant quantum spin chains are approximately integrable, and support long-lived quasiparticle excitations. A canonical example of integrable model of quantum magnetism is the XXZ spin chain, for which energy spreads ballistically, but, surprisingly, spin transport can be diffusive or superdiffusive. We review the transport properties of this model using an intuitive quasiparticle picture that relies on the recently introduced framework of generalized hydrodynamics. We discuss how anomalous linear response properties emerge from hierarchies of quasiparticles both in integrable and near-integrable limits, with an emphasis on the role of hydrodynamic fluctuations. We also comment on recent developments including non-linear response, full-counting statistics and far-from-equilibrium transport. We provide an overview of recent numerical and experimental results on transport in XXZ spin chains.
许多与实验相关的量子自旋链是近似可积的，并支持长寿命准粒子激发。量子磁体的可积模型的一个典型例子是 XXZ 自旋链，其能量呈弹道分布，但令人惊讶的是，自旋输运可以是扩散或超扩散的。我们使用最近引入的广义流体力学框架，基于直观的准粒子图像来综述该模型的输运性质。我们讨论了在可积和近可积极限下，准粒子的层次结构如何产生异常线性响应特性，重点讨论了流体力学涨落的作用。我们还评论了最近的发展，包括非线性响应、全计数统计和远离平衡的输运。我们概述了最近关于 XXZ 自旋链输运的数值和实验结果。
