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arXiv 2011.11504cond-mat.dis-nn
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多体局域化:自旋模型中的跃迁

Many-Body Localization: Transitions in Spin Models

John Schliemann, Joao Vitor I. Costa, Paul Wenk, J. Carlos Egues

摘要:

我们研究了自旋系统中各态历经相和多体定域相之间的转变,这些自旋系统受到淬火无序的影响,包括海森堡链和中心自旋模型。在这两种情况下,系统具有共同的自旋长度$1/2$和$1$通过精确的数值对角化和随机矩阵技术进行了研究。特别注意的是样品到样品的方差$(Δ_sr)^2$的平均召唤间隙比$\langle r\rangle$不同的障碍实现。对于这两种类型的系统和自旋长度,我们发现一个最大的$Δ_sr$作为无序强度的函数,伴随着一个拐点的$\langle r\rangle$,信号的过渡从遍历到多体局域化。临界无序强度被发现是有点小于最近的文献中报道的值。关于跃迁的进一步信息可以从给定无序实现内的期望值的概率分布中获得。

英文摘要:

We study the transitions between ergodic and many-body localized phases in spin systems, subject to quenched disorder, including the Heisenberg chain and the central spin model. In both cases systems with common spin lengths $1/2$ and $1$ are investigated via exact numerical diagonalization and random matrix techniques. Particular attention is paid to the sample-to-sample variance $(Δ_sr)^2$ of the averaged consecutive-gap ratio $\langle r\rangle$ for different disorder realizations. For both types of systems and spin lengths we find a maximum in $Δ_sr$ as a function of disorder strength, accompanied by an inflection point of $\langle r\rangle$, signaling the transition from ergodicity to many-body localization. The critical disorder strength is found to be somewhat smaller than the values reported in the recent literature. Further information about the transitions can be gained from the probability distribution of expectation values within a given disorder realization.

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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