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arXiv 1607.05656hep-thcond-mat.stat-mech
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有质量自由玻色子理论中的分支点扭场关联函数

Branch Point Twist Field Correlators in the Massive Free Boson Theory

Davide Bianchini, Olalla A. Castro-Alvaredo

摘要:

众所周知的一维多体量子系统中的纠缠度量,如纠缠熵和对数负性,可以用复制量子场论中称为分支点扭曲场的局域场的关联函数来表示。在这种“副本”的方法中,纠缠度的计算通常涉及副本数量的数学上非平凡的解析延拓。本文考虑1+1维有质量(非紧化)自由玻色子理论中扭场的两点函数及其解析延拓。这是已知扭转场的所有矩阵元的少数理论之一,因此我们可以希望非常精确地计算关联函数。研究了两个特殊的两点函数,它们分别与半无限不相交区间的对数负性和一个区间的纠缠熵有关。我们表明,我们的处方的解析延拓产生的结果是完全符合共形场论的预测在短距离的限制。我们提供了数值估计的通用量和它们的比率,无论是在无质量(扭曲场结构常数)和大规模(扭曲场的期望值)理论。我们发现,特定的比例是由不同的形状因子展开。我们提出这样的分歧干除了预期的幂律行为的两点函数在短距离的对数因子的存在。令人惊讶的是,在临界状态下,这些修正对长度为L的一个区间的纠缠熵产生log(logL)修正。这个迄今为止被忽视的结果与卡拉布雷斯、卡迪和托尼的结果一致,并由布隆多-富尼耶和多永独立推导出来(准备中)。

英文摘要:

Well-known measures of entanglement in one-dimensional many body quantum systems, such as the entanglement entropy and the logarithmic negativity, may be expressed in terms of the correlation functions of local fields known as branch point twist fields in a replica quantum field theory. In this "replica" approach the computation of measures of entanglement generally involves a mathematically non-trivial analytic continuation in the number of replicas. In this paper we consider two-point functions of twist fields and their analytic continuation in the 1+1 dimensional massive (non-compactified) free Boson theory. This is one of the few theories for which all matrix elements of twist fields are known so that we may hope to compute correlation functions very precisely. We study two particular two-point functions which are related to the logarithmic negativity of semi-infinite disjoint intervals and to the entanglement entropy of one interval. We show that our prescription for the analytic continuation yields results which are in full agreement with conformal field theory predictions in the short-distance limit. We provide numerical estimates of universal quantities and their ratios, both in the massless (twist field structure constants) and the massive (expectation values of twist fields) theory. We find that particular ratios are given by divergent form factor expansions. We propose such divergences stem from the presence of logarithmic factors in addition to the expected power-law behaviour of two-point functions at short-distances. Surprisingly, at criticality these corrections give rise to a log(logL) correction to the entanglement entropy of one interval of length L. This hitherto overlooked result is in agreement with results by Calabrese, Cardy and Tonni and has been independently derived by Blondeau-Fournier and Doyon (in preparation).

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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