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arXiv 1902.06100quant-phcond-mat.str-el
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有噪声Kitaev复曲面码模型中的相变

Phase transition in a noisy Kitaev toric code model

Mohammad Hossein Zarei, Afshin Montakhab

摘要:

众所周知,经典自旋模型的配分函数可以映射到量子纠缠态,在量子纠缠态的一边,某些性质可以用来发现另一边的新性质。然而,经典(临界)相变的存在对相应的量子态的影响大多被忽略了。这是特别有趣的,因为经典的配分函数在临界点处表现出非解析行为,并且这种行为可能在量子方面具有重要的后果。在本文中,我们考虑这个问题的一个重要的例子Kitaev复曲面代码模型已被证明是对应的二维(2D)伊辛模型,通过对偶变换。通过这样的对偶变换,它表明,在经典侧的温度映射到量子侧的位翻转噪声。结果表明,从一个给定的量子态的相干叠加到一个非相干的混合物的过渡正好对应于在伊辛模型的顺磁-铁磁相变。为了进一步确定这样的过渡,我们定义了一个序参量来表征这种混合物的退相干性,并表明它的行为类似于二维伊辛模型的序参量(磁化),这种行为被解释为在复曲面代码模型中的鲁棒一致性。此外,我们考虑的其他性质的噪声环面代码模型正是在临界点。我们发现,有一个相对稳定的复曲面代码状态的噪声在临界噪声,这是揭示了一个相对减少对噪声的敏感性。最后讨论了复曲面编码模型的鲁棒一致性和临界稳定性与拓扑序之间的关系。

英文摘要:

It is well-known that the partition function of a classical spin model can be mapped to a quantum entangled state where some properties on one side can be used to find new properties on the other side. However, the consequences of the existence of a classical (critical) phase transition on the corresponding quantum state has been mostly ignored. This is particularly interesting since the classical partition function exhibits non-analytic behavior at the critical point and such behavior could have important consequences on the quantum side. In this paper, we consider this problem for an important example of Kitaev toric code model which has been shown to correspond to the two-dimensional (2D) Ising model though a duality transformation. Through such duality transformation, it is shown that the temperature on the classical side is mapped to bit-flip noise on the quantum side. It is then shown that a transition from a coherent superposition of a given quantum state to a non-coherent mixture corresponds exactly to paramagnetic-ferromagnetic phase transition in the Ising model. To identify such a transition further, we define an order parameter to characterize the decoherency of such a mixture and show that it behaves similar to the order parameter (magnetization) of 2D Ising model, a behavior that is interpreted as a robust coherency in the toric code model. Furthermore, we consider other properties of the noisy toric code model exactly at the critical point. We show that there is a relative stability to noise for the toric code state at the critical noise which is revealed by a relative reduction in susceptibility to noise. We close the paper with a discussion on connection between the robust coherency as well as the critical stability with topological order of the toric code model.

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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