Universal Anomalous Diffusion of Quantized Vortices in Ultraquantum Turbulence
Universal Anomalous Diffusion of Quantized Vortices in Ultraquantum Turbulence
复制标题
超量子湍流中量子化涡旋的普遍反常扩散
DOI：
10.1103/physrevlett.129.025301
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发表时间：
2022
影响因子：
8.6
通讯作者：
Tsubota, Makoto
中科院分区：
文献类型：
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作者：
Yui, Satoshi;Tang, Yuan;Guo, Wei;Kobayashi, Hiromichi;Tsubota, Makoto
在经典的粘性流体中，湍流涡旋是嵌入颗粒快速扩散的原因。然而，在无粘量子流体中，湍流是由量子化涡旋的混沌缠结引起的，粒子的分散可以通过非经典机制实现，即，它们与不断演化的漩涡的结合然而，关于涡旋如何在量子流体湍流中扩散和传播的知识非常有限，特别是对于由涡旋随机缠结产生的所谓超量子湍流（UQT）。在这里，我们报告了一个系统的数值研究的涡在UQT在超流氦-4使用完整的Biot-Savart模拟的表观扩散。我们发现，在超流中的涡旋表现出普遍的反常扩散（超扩散）在小的时候，在大的时候过渡到正常扩散。这种行为被认为是一个通用的缩放特性的旋涡速度的结果。我们在有限温度下的模拟也很好地再现了最近的实验观察结果。从这项研究中获得的知识可能形成理解各种量子流体中的湍流输运和普遍涡旋动力学的基础。
In classical viscous fluids, turbulent eddies are known to be responsible for the rapid spreading of embedded particles. However, in inviscid quantum fluids where the turbulence is induced by a chaotic tangle of quantized vortices, dispersion of the particles can be achieved via a nonclassical mechanism, i.e., their binding to the evolving vortices. However, knowledge on how the vortices diffuse and spread in quantum-fluid turbulence is very limited, especially for the so-called ultraquantum turbulence (UQT) generated by a random tangle of vortices. Here we report a systematic numerical study of the apparent diffusion of vortices in UQT in superfluid helium-4 using the full Biot-Savart simulation. We reveal that the vortices in the superfluid exhibit a universal anomalous diffusion (superdiffusion) at small times, which transits to normal diffusion at large times. This behavior is found to be the result of a generic scaling property of the vortex velocity. Our simulation at finite temperatures also nicely reproduces recent experimental observations. The knowledge obtained from this study may form the base for understanding turbulent transport and universal vortex dynamics in various quantum fluids.