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arXiv 2302.01423quant-phcond-mat.dis-nnnlin.CD
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非厄米自旋链中的谱交叉:与随机矩阵理论的比较

Spectral crossover in non-hermitian spin chains: comparison with random matrix theory

Ayana Sarkar, Sunidhi Sen, Santosh Kumar

AI总结:

该研究系统研究非厄米自旋链的谱涨落,发现随机场导致可积性破缺和量子混沌,表现为从泊松到GinUE的谱交叉,并引入随机矩阵模型验证插值行为。

摘要:

我们使用复间距比系统研究了三个非厄米自旋链哈密顿量的短程谱涨落性质。我们特别关注标准一维各向异性XY模型的非厄米版本,该模型具有内在的旋转-时间反演($\mathcal{RT}$)对称性,Zhang和Song在[Phys.Rev.A \textbf{87}, 012114 (2013)]中对其进行了解析探索。相应的厄米对应物也是精确可解的,并已广泛用作凝聚态物理问题中的玩具模型。我们表明,沿$x$方向的随机场与沿$z$方向的随机场一起存在,促进了可积性和$\mathcal{RT}$对称性破缺,导致量子混沌行为的出现,这由类似于随机矩阵理论的泊松到Ginibre酉系综(GinUE)统计的谱交叉所指示。此外,我们考虑了两个$n \times n$维现象学随机矩阵模型,其中,取决于交叉参数,由复间距比测量的涨落性质显示出从1D-泊松到GinUE和从2D-泊松到GinUE行为的插值。这里1D和2D泊松分别对应于实部和复部不相关的能级。

英文摘要:

We systematically study the short range spectral fluctuation properties of three non-hermitian spin chain hamiltonians using complex spacing ratios. In particular we focus on the non-hermitian version of the standard one-dimensional anisotropic XY model having intrinsic rotation-time-reversal ($\mathcal{RT}$) symmetry that has been explored analytically by Zhang and Song in [Phys.Rev.A {\bf 87}, 012114 (2013)]. The corresponding hermitian counterpart is also exactly solvable and has been widely employed as a toy model in several condensed matter physics problems. We show that the presence of a random field along the $x$-direction together with the one along $z$ facilitates integrability and $\mathcal{RT}$-symmetry breaking leading to the emergence of quantum chaotic behaviour indicated by a spectral crossover resembling Poissonian to Ginibre unitary ensemble (GinUE) statistics of random matrix theory. Additionally, we consider two $n \times n$ dimensional phenomenological random matrix models in which, depending upon crossover parameters, the fluctuation properties measured by the complex spacing ratios show an interpolation between 1D-Poisson to GinUE and 2D-Poisson to GinUE behaviour. Here 1D and 2D Poisson correspond to real and complex uncorrelated levels, respectively.

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