摘要翻译：
在量子多体系统的有限温度行为中，我们面临着探测和表征量子临界足迹的问题。我们的策略是将具有t=0量子相变的系统的相图与其经典极限的相图进行比较，以找出真正的量子效应。为此，我们考虑了横场中的一维Ising模型：虽然量子S=1/2Ising链是精确可解的，并且得到了广泛的研究，但对于这类模型的经典极限（无穷大S）缺乏结果，我们在这里提供了它们。利用传输矩阵方法对它们进行了数值计算，并用自洽自旋波理论解析地导出了它们的渐近低温行为。我们按照量子分析中的相同步骤绘制了经典相图，发现这两个相图出乎意料地相似：在经典情况下也检测到三个相图，每个相图的特征是关联长度对温度和场的函数依赖关系类似于量子模型。经典情形与量子情形的区别在于进入这种依赖关系的指数的不同值，这是零温量子涨落相对于热涨落的不同性质的结果。
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英文标题：
《Extracting signatures of quantum criticality in the finite-temperature
  behavior of many-body systems》
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作者：
Alessandro Cuccoli, Alessio Taiti, Ruggero Vaia, Paola Verrucchi
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最新提交年份：
2007
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分类信息：

一级分类：Physics        物理学
二级分类：Statistical Mechanics        统计力学
分类描述：Phase transitions, thermodynamics, field theory, non-equilibrium phenomena, renormalization group and scaling, integrable models, turbulence
相变，热力学，场论，非平衡现象，重整化群和标度，可积模型，湍流
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英文摘要：
  We face the problem of detecting and featuring footprints of quantum criticality in the finite-temperature behavior of quantum many-body systems. Our strategy is that of comparing the phase diagram of a system displaying a T=0 quantum phase transition with that of its classical limit, in order to single out the genuinely quantum effects. To this aim, we consider the one-dimensional Ising model in a transverse field: while the quantum S=1/2 Ising chain is exactly solvable and extensively studied, results for the classical limit (infinite S) of such model are lacking, and we supply them here. They are obtained numerically, via the Transfer-matrix method, and their asymptotic low-temperature behavior is also derived analytically by self-consistent spin-wave theory. We draw the classical phase-diagram according to the same procedure followed in the quantum analysis, and the two phase diagrams are found unexpectedly similar: Three regimes are detected also in the classical case, each characterized by a functional dependence of the correlation length on temperature and field analogous to that of the quantum model. What discriminates the classical from the quantum case are the different values of the exponents entering such dependencies, a consequence of the different nature of zero-temperature quantum fluctuations with respect to thermal ones.
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PDF链接：
https://arxiv.org/pdf/708.1142