arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 2011.06611cond-mat.str-elcond-mat.stat-mechquant-ph
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拓扑相变及以后的纠缠序参量和临界行为

Entanglement order parameters and critical behavior for topological phase transitions and beyond

Mohsin Iqbal, Norbert Schuch

摘要:

拓扑相位是一种奇异的量子相位,它缺乏序参量的表征。在本文中,我们开发了一个统一的框架的基础上变分iPEPS的拓扑和常规相变通过纠缠序参量的定量研究。为此,我们采用张量网络与适当的物理和/或纠缠对称性编码,并允许序参量检测任何这些对称性的行为,物理和纠缠的。首先,这引起了基于纠缠的序参量的拓扑相位。这些拓扑序参量允许定量探测拓扑相变,并确定其普遍的行为。我们将我们的框架应用于研究不同磁场中的Toric Code模型,在某些情况下,它映射到(2+1)D伊辛模型。我们确定了整个过渡的三维伊辛临界指数,与这些特殊情况和一般信念一致。然而,我们还发现一个未知的临界指数β =0.021。然后,我们将我们的纠缠序参量的框架,以传统的相变。我们构造了一种新型的无序算子(或无序参数),它在无序相中是非零的,并测量了波函数对纠缠中对称扭曲的响应。我们数值计算了(2+1)D横向场伊辛模型的无序算子,在那里我们再次恢复了一个临界指数,迄今为止未知的模型,β =0.024,与复曲面代码的结果一致。这表明,纠缠序参量可以提供额外的手段,在拓扑和传统的相变的通用数据的特征,并完全展示了这个框架的权力,以确定通用数据的过渡。

英文摘要:

Topological phases are exotic quantum phases which are lacking the characterization in terms of order parameters. In this paper, we develop a unified framework based on variational iPEPS for the quantitative study of both topological and conventional phase transitions through entanglement order parameters. To this end, we employ tensor networks with suitable physical and/or entanglement symmetries encoded, and allow for order parameters detecting the behavior of any of those symmetries, both physical and entanglement ones. First, this gives rise to entanglement-based order parameters for topological phases. These topological order parameters allow to quantitatively probe topological phase transitions and to identify their universal behavior. We apply our framework to the study of the Toric Code model in different magnetic fields, which in some cases maps to the (2+1)D Ising model. We identify 3D Ising critical exponents for the entire transition, consistent with those special cases and general belief. However, we moreover find an unknown critical exponent beta=0.021. We then apply our framework of entanglement order parameters to conventional phase transitions. We construct a novel type of disorder operator (or disorder parameter), which is non-zero in the disordered phase and measures the response of the wavefunction to a symmetry twist in the entanglement. We numerically evaluate this disorder operator for the (2+1)D transverse field Ising model, where we again recover a critical exponent hitherto unknown in the model, beta=0.024, consistent with the findings for the Toric Code. This shows that entanglement order parameters can provide additional means of characterizing the universal data both at topological and conventional phase transitions, and altogether demonstrates the power of this framework to identify the universal data underlying the transition.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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