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arXiv 1302.5836cond-mat.stat-mechcond-mat.str-el
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场论和可积系统中的量子关联

Quantum Correlations in Field Theory and Integrable Systems

Stefano Evangelisti

摘要:

在这篇博士论文中,我们研究了一维量子系统的一些性质,重点是可积模型的两个重要方面:它们在平衡态的纠缠性质和量子猝灭后的动力学量子化。因此,本论文的第一部分将致力于研究一维可积系统中的纠缠熵,特别关注XYZ自旋-1/2链,它除了是可积的之外,也是一个具有非微扰解的相互作用理论。我们推导出它的二分Renyi熵的热力学极限和它的行为在不同的阶段和不同的值的质量间隙进行了分析,分析和数值。特别值得一提的是,本文所提出的XYZ模型熵的数值分析在文献中从未发表过。在论文的第二部分中,我们研究了量子猝灭后的双光子系统的动力学,使系统处于压缩相干初态。重点是横向场伊辛链和O(3)非线性西格玛模型,后者用半经典理论研究,前者用形状因子方法研究。此外,在最后一章中,我们概述了量子猝灭后局域观测量的关联函数动力学的一般结果。特别是,我们表明,如果没有长程相互作用的最终哈密顿量,然后在长时间(非等时相关)的模型的动力学描述的统计系综,描述其静态属性(等时相关)。对于横场伊辛链,这一结果意味着它的动力学是由广义吉布斯熵描述的。

英文摘要:

In this PhD thesis we investigate some properties of one-dimensional quantum systems, focusing on two important aspects of integrable models: Their entanglement properties at equilibrium and their dynamical correlators after a quantum quench. The first part of the thesis will therefore be devoted to the study of the entanglement entropy in one-dimensional integrable systems, with a special focus on the XYZ spin-1/2 chain, which, in addition to being integrable, is also an interacting theory with non perturbative solutions. We derive its bipartite Renyi entropies in the thermodynamic limit and its behaviour in different phases and for different values of the mass-gap is analysed, both analytically and numerically. In particular it is worth mentioning that the numerical analysis of the entropies of the XYZ model presented in this dissertation has never been published in literature. In the second part of the thesis we study the dynamics of correlators after a quantum quench, preparing the system in a squeezed coherent initial state. The emphasis will be on the Transverse Field Ising Chain and the O(3) non-linear sigma model, the latter studied by means of the semi-classical theory, the former by a form-factor approach. Moreover in the last chapter we outline a general result about the dynamics of correlation functions of local observables after a quantum quench. In particular we show that if there are not long-range interactions in the final Hamiltonian, then the dynamics of the model at long times (non equal- time correlations) is described by the same statistical ensemble that describes its statical properties (equal-time correlations). For the Transverse Field Ising Chain this result means that its dynamics is described by a Generalized Gibbs Ensemble.

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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