Nonequilibrium Criticality in Quench Dynamics of Long-Range Spin Models
Nonequilibrium Criticality in Quench Dynamics of Long-Range Spin Models
复制标题
长程自旋模型淬火动力学中的非平衡临界
DOI：
10.1103/physrevlett.125.040602
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发表时间：
2020
影响因子：
8.6
通讯作者：
Maghrebi, Mohammad F.
中科院分区：
文献类型：
--
作者：
Titum, Paraj;Maghrebi, Mohammad F.
远程相互作用自旋系统在物理学中普遍存在，并表现出各种基态无序到有序的相变。我们考虑了一个称为Lipkin-Meshkov-Glick模型的无限范围相互作用模型的原型，该模型描述了自旋的集体相互作用，并研究了哈密顿量突然猝灭后波动和相关性的动力学性质。具体来说，我们关注临界淬火，其中初始状态和/或后淬火哈密顿量是临界的。根据淬灭的类型，我们确定了三种不同的行为，其中短时动态和长时间的稳态都是有效的热态、量子态和真正的非平衡态，其特征是不同的普适性类别以及静态和动态临界指数。这些行为可以通过红外有效温度来识别，红外有效温度分别为有限、零和无限（后者随系统大小的变化而变化）。利用非平衡Keldysh场理论，通过精确数值和解析计算相结合的方法研究了淬火动力学。我们的结果可以在自然产生远程相互作用的捕获离子实验中实现。
Long-range interacting spin systems are ubiquitous in physics and exhibit a variety of ground-state disorder-to-order phase transitions. We consider a prototype of infinite-range interacting models known as the Lipkin-Meshkov-Glick model describing the collective interaction ofspins and investigate the dynamical properties of fluctuations and correlations after a sudden quench of the Hamiltonian. Specifically, we focus on critical quenches, where the initial state and/or the postquench Hamiltonian are critical. Depending on the type of quench, we identify three distinct behaviors where both the short-time dynamics and the stationary state at long times are effectively thermal, quantum, and genuinely nonequilibrium, characterized by distinct universality classes and static and dynamical critical exponents. These behaviors can be identified by an infrared effective temperature that is finite, zero, and infinite (the latter scaling with the system size as), respectively. The quench dynamics is studied through a combination of exact numerics and analytical calculations utilizing the nonequilibrium Keldysh field theory. Our results are amenable to realization in experiments with trapped-ion experiments where long-range interactions naturally arise.