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arXiv 1111.0420cond-mat.stat-mechquant-ph
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无限维结构横场量子伊辛模型的量子蒙特卡罗研究

Quantum Monte Carlo study of the transverse-field quantum Ising model on infinite-dimensional structures

Seung Ki Baek, Jaegon Um, Su Do Yi, Beom Jun Kim

摘要:

在许多经典的物理模型中,存在一个称为上临界维数的特征维数,在该上临界维数之上,人们观察到平均场临界行为。然而,人们也可以考虑无限维结构,而不是构造高维晶格,问题是这种平均场特征是否也延伸到量子力学的情况。因此,我们利用量子蒙特卡罗模拟和有限尺寸标度分析研究了全局耦合网络和Watts-Strogatz小世界网络上的横场量子伊辛模型.我们确认,这两种结构表现出临界行为与平均场描述一致。特别是,我们表明,现有的累积量方法在估计正确的动态临界指数有困难,并建议,一个序参量的基础上的量子力学的期望值可以是一个实际有用的数值观测,以确定临界行为时,没有明确定义的维数。

英文摘要:

In a number of classical statistical-physical models, there exists a characteristic dimensionality called the upper critical dimension above which one observes the mean-field critical behavior. Instead of constructing high-dimensional lattices, however, one can also consider infinite-dimensional structures, and the question is whether this mean-field character extends to quantum-mechanical cases as well. We therefore investigate the transverse-field quantum Ising model on the globally coupled network and the Watts-Strogatz small-world network by means of quantum Monte Carlo simulations and the finite-size scaling analysis. We confirm that both the structures exhibit critical behavior consistent with the mean-field description. In particular, we show that the existing cumulant method has a difficulty in estimating the correct dynamic critical exponent and suggest that an order parameter based on the quantum-mechanical expectation value can be a practically useful numerical observable to determine critical behavior when there is no well-defined dimensionality.

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