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arXiv 2004.06678cond-mat.stat-mech
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太接近可积:从正常热扩散到反常热扩散的交叉

Too Close to Integrable: Crossover from Normal to Anomalous Heat Diffusion

Stefano Lepri, Roberto Livi, Antonio Politi

摘要:

具有三个守恒律的一维粒子链中的能量输运一般是反常的,属于Kardar-Parisi-Zhang动力学普适类。令人惊讶的是,一些例子中,一个明显的正常的热扩散被发现在一个大范围的长度尺度的报告。我们提出了一个新的物理解释这些有趣的观察。我们开发了一个尺度分析,解释了这可能发生在附近的可积极限,如,但不仅是,著名的户田模型。在这个极限下,热传输主要由具有非常大的平均自由程$\ell$的准粒子提供。在增加系统尺寸$L$时,可以观察到三种不同的区域:弹道区域、中间扩散区域以及最终到异常(流体动力学)区域的交叉区域。我们的理论考虑是支持的数值模拟的气体的双原子硬点粒子几乎相同的质量和弱扰动户田链。最后,我们讨论的情况下,扰动谐波链,它表现出一个不同的情况。

英文摘要:

Energy transport in one-dimensional chains of particles with three conservation laws is generically anomalous and belongs to the Kardar-Parisi-Zhang dynamical universality class. Surprisingly, some examples where an apparent normal heat diffusion is found over a large range of length scales were reported. We propose a novel physical explanation of these intriguing observations. We develop a scaling analysis which explains how this may happen in the vicinity of an integrable limit, such as, but not only, the famous Toda model. In this limit, heat transport is mostly supplied by quasi-particles with a very large mean free path $\ell$. Upon increasing the system size $L$, three different regimes can be observed: a ballistic one, an intermediate diffusive range, and, eventually, the crossover to the anomalous (hydrodynamic) regime. Our theoretical considerations are supported by numerical simulations of a gas of diatomic hard-point particles for almost equal masses and of a weakly perturbed Toda chain. Finally, we discuss the case of the perturbed harmonic chain, which exhibits a yet different scenario.

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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