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arXiv 2103.14020cond-mat.dis-nncond-mat.quant-gascond-mat.stat-mechcond-mat.str-el
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约束诱导离域

Constraints induced delocalization

Piotr Sierant, Eduardo Gonzalez Lazo, Marcello Dalmonte, Antonello Scardicchio, Jakub Zakrzewski

摘要:

我们研究了淬火无序对描述一维里德伯原子阵列的局域约束量子自旋链动力学的影响。进行大规模的数值实验,我们没有观察到任何痕迹的多体局域化,即使在大的混乱。分析约束系统中的淬火无序条款的作用,我们表明,他们的行为在两个,不同的和竞争的方式:作为一个网站的基本激发系统的无序条款,并作为激发之间的相互作用。这两个贡献是相同的顺序,当它们竞争时(一个朝向定域化,另一个反对),它们永远不会进入真正的强无序、弱相互作用极限,在那里发生多体局域化。这种机制在XY型约束模型的情况下得到了进一步的阐明:在那里,一个表示作用于干净模型激发的真正的局部淬火无序项的项必须被写为一系列非局部项的无约束变量。我们的观察提供了一个简单的图片来解释淬火无序的作用,可以立即扩展到其他约束模型或淬火规范理论。

英文摘要:

We study the impact of quenched disorder on the dynamics of locally constrained quantum spin chains, that describe 1D arrays of Rydberg atoms in both frozen (Ising-type) and dressed (XY-type) regime. Performing large-scale numerical experiments, we observe no trace of many-body localization even at large disorder. Analyzing the role of quenched disorder terms in constrained systems we show that they act in two, distinct and competing ways: as an on-site disorder term for the basic excitations of the system, and as an interaction between excitations. The two contributions are of the same order, and as they compete (one towards localization, the other against it), one does never enter a truly strong disorder, weak interaction limit, where many-body localization occurs. Such a mechanism is further clarified in the case of XY-type constrained models: there, a term which would represent a bona-fide local quenched disorder term acting on the excitations of the clean model must be written as a series of non-local terms in the unconstrained variables. Our observations provide a simple picture to interpret the role of quenched disorder that could be immediately extended to other constrained models or quenched gauge theories.

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