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arXiv 2108.12583cond-mat.dis-nn
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幂律随机带状矩阵作为多体局域化相变的有效模型

Power-Law Random Banded Matrix Ensemble as the Effective Model for Many-Body Localization Transition

Wen-Jia Rao

摘要:

采用具有单调谐参数$μ$的幂律随机带矩阵系综作为随机自旋系统多体局域化跃迁的有效模型。我们表明PRBM准确地再现本征值统计的整个相图通过拟合的高阶间距比分布$P(r^{(n)})$以及数方差$Σ^{2}(l)$,在系统中有和没有时间反演对称性。对于本征矢量的性质,研究表明PRBM的纠缠熵呈现出从体积律到面积律的演化过程,这是一个各态历经的MBL跃迁,其临界指数为$ν=0.83\pm 0.15$,接近于一维物理模型中通过精确对角化得到的值,而计算量要小得多。

英文摘要:

We employ the power-law random band matrix (PRBM) ensemble with single tuning parameter $μ$ as the effective model for many-body localization (MBL) transition in random spin systems. We show the PRBM accurately reproduce the eigenvalue statistics on the entire phase diagram through the fittings of high-order spacing ratio distributions $P(r^{(n)})$ as well as number variance $Σ^{2}(l)$, in systems both with and without time-reversal symmetry. For the properties of eigenvectors, it's shown the entanglement entropy of PRBM displays an evolution from volume-law to area-law behavior which signatures an ergodic-MBL transition, and the critical exponent is found to be $ν=0.83\pm 0.15$, close to the value obtained in 1D physical model by exact diagonalization while the computational cost here is much less.

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