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arXiv 0811.1616cond-mat.str-el
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表征Haltron相的弦序参量的有限尺寸标度

Finite-size scaling of string order parameters characterizing the Haldane phase

Hiroshi Ueda, Hiroki Nakano, Koichi Kusakabe

摘要:

我们发展了一种数值方法,通过分析表征基态的多点关联函数来阐明量子相变附近的临界行为。本文成功地将此方法应用于单轴离子各向异性的S = 1 XXZ链的弦序参量。用密度矩阵重整化群方法估计了有限尺寸弦关联函数。我们重点研究了对数图上的关联函数的反系统梯度与系统大小的关系.这个量表明,有限尺寸标度在临界点敏感地变化。当系统处于无序相、临界点或有序相时,梯度随系统尺寸增加的行为分别是发散的、稳定在有限值的或迅速减小到零的。通过对有限长串关联函数的分析,可以精确地确定Haldle相位的边界和估计关联长度的临界指数。我们的估计的转变点和临界指数,这是由基态量,是一致的,从能级结构的分析得到的结果。我们的分析只需要几个有限大小的关联函数在相同的条件下作为候选的长程序。无论破坏有关秩序的要素是什么,数量都以同样的方式处理。这项工作将有助于发展一种直接观察量子相变的方法。

英文摘要:

We have developed a numerical procedure to clarify the critical behavior near a quantum phase transition by analyzing a multi-point correlation function characterizing the ground state. This work presents a successful application of this procedure to the string order parameter of the S = 1 XXZ chain with uniaxial single-ion anisotropy. The finite-size string correlation function is estimated by the density matrix renormalization group method. We focus on the gradient of the inversedsystem- size dependence of the correlation function on a logarithmic plot. This quantity shows that the finite-size scaling sensitively changes at the critical point. The behavior of the gradient with increasing system size is divergent, stable at a finite value, or rapidly decreases to zero when the system is in the disordered phase, at the critical point, or in the ordered phase, respectively. The analysis of the finite-size string correlation functions allows precise determination of the boundary of the Haldane phase and estimation of the critical exponent of the correlation length. Our estimates of the transition point and the critical exponents, which are determined only by the ground-state quantities, are consistent with results obtained from the analysis of the energy-level structure. Our analysis requires only the correlation functions of several finite sizes under the same condition as a candidate for the long-range order. The quantity is treated in the same manner irrespective of the kind of elements which destroy the order concerned. This work will assist in the development of a method to directly observe quantum phase transitions.

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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