论文标题

重新归一化的Lindblad驾驶:数字脱离量子杂质求解器

Renormalized Lindblad Driving: A Numerically-Exact Nonequilibrium Quantum Impurity Solver

论文作者

Lotem, Matan, Weichselbaum, Andreas, von Delft, Jan, Goldstein, Moshe

论文摘要

在多体物理学中,非平衡非常相关的量子系统的准确表征一直是一个长期的挑战。其中值得注意的是量子杂质模型,这些模型出现在各种纳米电子和量子计算应用中。尽管它们看起来很简单,但它们具有相关的现象,包括新兴的能量尺度和非富特液体物理学,需要重新归一化组的治疗。这通常与在有限偏见下对其非平衡稳态的描述不一致,后者将其本质暴露为开放量子系统。我们提出了一种新型的数值脱颖而出的方法,用于获得在任意电压或温度偏置下与金属铅耦合的一般量子杂质的非平衡状态,我们称之为“ RL- sense”(重新归一化的Lindblad驱动的非平衡稳态)。它是基于将杂质与完全处理的离散铅的相干耦合。此外,这些导线与Lindblad动力学所描述的储层相结合,这些动力学施加了电压或温度偏置。除了先前的尝试之外,我们还将与威尔逊的数值重新归一化组一起利用铅的混合离散方案,以探测指数小的能量尺度。然后通过实时lindblad动力学通过进化矩阵 - 产物密度运算符来发现稳态,并采用了时间依赖性密度矩阵重量化组的耗散概括。在长期限制中,由于引入的耗散,该过程在有限债券维度下会收敛到稳态,从而限制了纠缠的生长。我们针对非相互作用谐振水平模型的精确解决方案测试该方法。我们使用交互的两级模型来演示其功能,为此,它正确地重现了已知限制,并在它们之间提供了完整的$ i $ - $ v $曲线。

The accurate characterization of nonequilibrium strongly-correlated quantum systems has been a longstanding challenge in many-body physics. Notable among them are quantum impurity models, which appear in various nanoelectronic and quantum computing applications. Despite their seeming simplicity, they feature correlated phenomena, including emergent energy scales and non-Fermi-liquid physics, requiring renormalization group treatment. This has typically been at odds with the description of their nonequilibrium steady-state under finite bias, which exposes their nature as open quantum systems. We present a novel numerically-exact method for obtaining the nonequilibrium state of a general quantum impurity coupled to metallic leads at arbitrary voltage or temperature bias, which we call "RL-NESS" (Renormalized Lindblad-driven NonEquilibrium Steady-State). It is based on coherently coupling the impurity to discretized leads which are treated exactly. These leads are furthermore weakly coupled to reservoirs described by Lindblad dynamics which impose voltage or temperature bias. Going beyond previous attempts, we exploit a hybrid discretization scheme for the leads together with Wilson's numerical renormalization group, in order to probe exponentially small energy scales. The steady-state is then found by evolving a matrix-product density operator via real-time Lindblad dynamics, employing a dissipative generalization of the time-dependent density matrix renormalization group. In the long-time limit, this procedure converges to the steady-state at finite bond dimension due to the introduced dissipation, which bounds the growth of entanglement. We test the method against the exact solution of the noninteracting resonant level model. We demonstrate its power using an interacting two-level model, for which it correctly reproduces the known limits, and gives the full $I$-$V$ curve between them.

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