In this paper we give an overview of some recent progress in using holography to study various far-from-equilibrium condensed matter systems. Non-equilibrium problems are notoriously difficult to deal with, not to mention at strong coupling and including quantum effects. Remarkably, using holographic duality one can describe and follow the real time evolution of far-from-equilibrium systems, including those which are spatially inhomogeneous and anisotropic, by solving partial differential gravity equations (PDEs). We sample developments on two broad classes of questions which are of much recent interest in the condensed matter community: non-equilibrium steady states (NESS), and quantum systems undergoing a global quench. Our discussion focuses on the main physical insights obtained from the gravity approaches, rather than comprehensive treatments of each topic or detailed descriptions of gravity calculations. The paper also includes an overview of current numerical techniques, as well as the holographic Schwinger-Keldysh approach to real-time correlation functions.

中文翻译：

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远离平衡的全息系统：综述

在本文中，我们概述了使用全息术研究各种远离平衡的凝聚态系统的最新进展。众所周知，非平衡问题很难处理，更不用说强耦合和量子效应了。值得注意的是，使用全息二元性可以通过求解偏微分重力方程 (PDE) 来描述和跟踪远离平衡系统的实时演化，包括那些空间不均匀和各向异性的系统。我们对凝聚态物质界最近很感兴趣的两大类问题的发展进行了抽样调查：非平衡稳态 (NESS) 和经历全局猝灭的量子系统。我们的讨论集中在从重力方法中获得的主要物理见解，而不是每个主题的综合处理或重力计算的详细描述。该论文还概述了当前的数值技术，以及实时相关函数的全息 Schwinger-Keldysh 方法。