近日，美国普林斯顿大学的Ewan McCulloch及其研究团队取得一项新进展。他们揭示了狄拉克流体中的非高斯扩散涨落。相关研究成果已于2024年12月4日在国际知名学术期刊《美国科学院院刊》上发表。

本文指出相对论流体动力学波动的一个显著后果：电荷传输的全计数统计（FCS）呈现出高度非高斯性。研究人员预测了FCS的确切渐近形式，这一预测推广了先前针对某些可积相互作用系统所得出的结果。由此得出，在准一维非平衡初始条件下，流体动力学区域中的电荷噪声相较于传统扩散金属中的噪声，会得到参数性的增强。

据悉，狄拉克流体——遵循粒子-空穴对称性和洛伦兹不变性的相互作用系统——属于最简单的流体动力学系统之一，它们也被研究作为强相互作用狄拉克半金属中传输特性的有效描述。狄拉克流体的直接实验特征难以捉摸，因为其电荷传输与常规金属一样呈扩散性。

附：英文原文

Title: Non-Gaussian diffusive fluctuations in Dirac fluids

Author: Gopalakrishnan, Sarang, McCulloch, Ewan, Vasseur, Romain

Issue&Volume: 2024-12-4

Abstract: Dirac fluids—interacting systems obeying particle–hole symmetry and Lorentz invariance—are among the simplest hydrodynamic systems; they have also been studied as effective descriptions of transport in strongly interacting Dirac semimetals. Direct experimental signatures of the Dirac fluid are elusive, as its charge transport is diffusive as in conventional metals. In this paper, we point out a striking consequence of fluctuating relativistic hydrodynamics: The full counting statistics (FCS) of charge transport is highly non-Gaussian. We predict the exact asymptotic form of the FCS, which generalizes a result previously derived for certain interacting integrable systems. A consequence is that, starting from quasi-one-dimensional nonequilibrium initial conditions, charge noise in the hydrodynamic regime is parametrically enhanced relative to that in conventional diffusive metals.

DOI: 10.1073/pnas.2403327121

Source: https://www.pnas.org/doi/abs/10.1073/pnas.2403327121