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arXiv 2104.11325quant-phnlin.CD
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混合型台球系统混沌本征态局部化测度的统计特性及谱统计

Statistical properties of the localization measure of chaotic eigenstates and the spectral statistics in a mixed-type billiard

Benjamin Batistić, Črt Lozej, Marko Robnik

摘要:

本文研究了混合型相空间中台球混沌本征态的量子局域化,在将规则本征态和混沌本征态分离后,在微扭曲的圆形台球区域中,尽管扩散不是正态的,但经典输运时间仍然足够大.在具有离散能谱的量子系统中,Heisenberg时间$t_H =2π\hbar/ΔE$($ΔE$是平均能级间距)是一个重要的时间尺度,经典输运时间尺度$t_T$与Heisenberg时间尺度$t_H$的比值(参数$α=t_H/t_T$)决定了混沌本征态的局域化程度,其度量$A$是基于信息熵的.我们发现,$A$是线性相关的归一化逆参与率。混沌本征态的局部化也反映在最近能级之间的分数幂律排斥中,在这个意义上,在距离$S$上找到连续能级的概率密度类似于小$S$的$\propto S^β$,其中$0\leqβ\leq1$和$β=1$对应于完全扩展的状态。我们表明,水平排斥指数$β$是经验的$α$的有理函数,和平均值$\langle A \rangle$作为$α$的函数也很好地近似由有理函数。在这两种情况下,平均曲线周围的经验数据都有一些分散,这是由于$A$实际上有一个分布,通常具有相当复杂的结构,但在极限$α\rightarrow \infty$中,β分布很好地描述了$α\rightarrow \infty$。与其他系统一样,当$α$从$0$变为$\infty$时,$β$从$0$变为$1$。$β$是$\langle A \rangle$的函数,类似于量子踢旋转器和体育场台球。

英文摘要:

We study the quantum localization in the chaotic eigenstates of a billiard with mixed-type phase space, after separating the regular and chaotic eigenstates, in the regime of slightly distorted circle billiard where the classical transport time in the momentum space is still large enough, although the diffusion is not normal. In quantum systems with discrete energy spectrum the Heisenberg time $t_H =2π\hbar/ΔE$, where $ΔE$ is the mean level spacing, is an important time scale.The classical transport time scale $t_T$ in relation to the Heisenberg time scale $t_H$ (their ratio is the parameter $α=t_H/t_T$) determines the degree of localization of the chaotic eigenstates, whose measure $A$ is based on the information entropy. We show that $A$ is linearly related to normalized inverse participation ratio. The localization of chaotic eigenstates is reflected also in the fractional power-law repulsion between the nearest energy levels in the sense that the probability density to find successive levels on a distance $S$ goes like $\propto S^β$ for small $S$, where $0\leqβ\leq1$, and $β=1$ corresponds to completely extended states. We show that the level repulsion exponent $β$ is empirically a rational function of $α$, and the mean $\langle A \rangle$ as a function of $α$ is also well approximated by a rational function. In both cases there is some scattering of the empirical data around the mean curve, which is due to the fact that $A$ actually has a distribution, typically with quite complex structure, but in the limit $α\rightarrow \infty$ well described by the beta distribution. Like in other systems, $β$ goes from $0$ to $1$ when $α$ goes from $0$ to $\infty$. $β$ is a function of $\langle A \rangle$, similar to the quantum kicked rotator and the stadium billiard.

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