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arXiv 2002.00875cond-mat.stat-mech
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二维经典硬棒模型相变处纠缠熵不存在对数发散

Absence of logarithmic divergence of the entanglement entropies at the phase transitions of a 2D classical hard rod model

Christophe Chatelain, Andrej Gendiar

AI总结:

本文用新提出的CTMRG算法研究二维正方格点硬棒模型,发现其相变处纠缠熵无对数发散,从而推断该相变既不属于Ising普适类也非一级相变。

摘要:

纠缠熵是探测量子系统及经典系统中连续、不连续乃至拓扑相变的有力工具。本文在正方形几何构型下对经典格点模型的冯·诺依曼纠缠熵和Renyi纠缠熵进行了数值研究。从正方形中心到其一条边(例如右边)的中点作一截线,纠缠熵度量系统左半部分与右半部分之间的纠缠。与条形几何构型中一样,冯·诺依曼纠缠熵和Renyi纠缠熵在相变点呈对数发散,而在一级相变处则表现为跳变。该分析被推广到一个经典模型,该模型由沉积在正方格点上的互不重叠的有限硬棒组成。蒙特卡洛模拟表明,当硬棒跨越7个或更多格点时,相图中在两个无序相之间会出现一个向列相。本文引入了一种新的角转移矩阵重整化群算法(CTMRG)来研究该模型。在此讨论的CTMRG计算中,相变处未观察到纠缠熵的对数发散。因此我们推断,这些相变既不可能属于文献中先前假设的Ising普适类,也不可能是非连续的。

英文摘要:

Entanglement entropy is a powerful tool to detect continuous, discontinuous and even topological phase transitions in quantum as well as classical systems. In this work, von Neumann and Renyi entanglement entropies are studied numerically for classical lattice models in a square geometry. A cut is made from the center of the square to the midpoint of one of its edges, say the right edge. The entanglement entropies measure the entanglement between the left and right halves of the system. As in the strip geometry, von Neumann and Renyi entanglement entropies diverge logarithmically at the transition point while they display a jump for first-order phase transitions. The analysis is extended to a classical model of non-overlapping finite hard rods deposited on a square lattice for which Monte Carlo simulations have shown that, when the hard rods span over 7 or more lattice sites, a nematic phase appears in the phase diagram between two disordered phases. A new Corner Transfer Matrix Renormalization Group algorithm (CTMRG) is introduced to study this model. No logarithmic divergence of entanglement entropies is observed at the phase transitions in the CTMRG calculation discussed here. We therefore infer that the transitions neither can belong to the Ising universality class, as previously assumed in the literature, nor be discontinuous.

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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