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arXiv 1608.04074cond-mat.str-elhep-thquant-ph
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量子链中选择性测量后的纠缠熵

Entanglement entropy after selective measurements in quantum chains

Khadijeh Najafi, M. A. Rajabpour

摘要:

研究了量子链中选择性测量后的二体后测量纠缠熵。首先研究了共形场论所能描述的临界系统的数量。我们发现后测量的纠缠熵和卡西米尔能量的浮动对象之间的连接。在此基础上,给出了开放系统和有限温度系统的后测量纠缠熵的计算公式。我们还评论了Affleck-Ludwig边界熵的背景下,后测量纠缠熵。最后,我们还给出了测量后系统的模哈密顿量和纠缠谱的计算公式。通过对CFT系统的讨论,我们也给出了一些关于大质量场论的预言。然后讨论了一种计算自由费米子系统后测量纠缠熵的通用方法。利用该方法研究了XY自旋链中的后测量纠缠熵。数值检验了横场伊辛链和XX模型中的CFT和质量场论结果。特别地,我们研究了无限周期开放临界横场Ising链和临界XX模型中的后测纠缠熵。在这些模型中还讨论了温度和间隙的影响。

英文摘要:

We study bipartite post measurement entanglement entropy after selective measurements in quantum chains. We first study the quantity for the critical systems that can be described by conformal field theories. We find a connection between post measurement entanglement entropy and the Casimir energy of floating objects. Then we provide formulas for the post measurement entanglement entropy for open and finite temperature systems. We also comment on the Affleck-Ludwig boundary entropy in the context of the post measurement entanglement entropy. Finally, we also provide some formulas regarding modular hamiltonians and entanglement spectrum in the after measurement systems. After through discussion regarding CFT systems we also provide some predictions regarding massive field theories. We then discuss a generic method to calculate the post measurement entanglement entropy in the free fermion systems. Using the method we study the post measurement entanglement entropy in the XY spin chain. We check numerically the CFT and the massive field theory results in the transverse field Ising chain and the XX model. In particular, we study the post meaurement entanglement entropy in the infinite, periodic and open critical transverse field Ising chain and the critical XX model. The effect of the temperature and the gap is also discussed in these models.

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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