近日，德国慕尼黑大学的Immanuel Bloch&Julian F. Wienand及其研究团队取得一项新进展。经过不懈努力，他们揭示混沌量子系统中波动流体力学的出现。相关研究成果已于2024年8月12日在国际知名学术期刊《自然—物理学》上发表。

该研究团队进行了大规模量子模拟，监测了硬核玻色子可调梯状结构中的粒子数波动，并探索了当系统从可积动力学过渡到完全混沌动力学时，波动的累积如何变化。

研究结果表明，远离平衡的混沌系统中大规模波动的增长由平衡态传输系数定量决定，这与波动流体力学的预测一致。子系统波动的这种新兴流体力学行为为远离平衡的涨落-耗散关系提供了检验，并允许使用远离平衡的量子动力学准确确定平衡态传输系数。

据悉，混沌量子动力学的一个基本原理是，局部子系统最终会接近热平衡态。由于平衡受限于在扩展长度尺度上波动的流体动力学累积，因此相应的时间尺度会随着子系统大小的增加而增加。

附：英文原文

Title: Emergence of fluctuating hydrodynamics in chaotic quantum systems

Author: Wienand, Julian F., Karch, Simon, Impertro, Alexander, Schweizer, Christian, McCulloch, Ewan, Vasseur, Romain, Gopalakrishnan, Sarang, Aidelsburger, Monika, Bloch, Immanuel

Issue&Volume: 2024-08-12

Abstract: A fundamental principle of chaotic quantum dynamics is that local subsystems eventually approach a thermal equilibrium state. The corresponding timescales increase with subsystem size as equilibration is limited by the hydrodynamic build-up of fluctuations on extended length scales. We perform large-scale quantum simulations that monitor particle-number fluctuations in tunable ladders of hard-core bosons and explore how the build-up of fluctuations changes as the system crosses over from integrable to fully chaotic dynamics. Our results indicate that the growth of large-scale fluctuations in chaotic, far-from-equilibrium systems is quantitatively determined by equilibrium transport coefficients, in agreement with the predictions of fluctuating hydrodynamics. This emergent hydrodynamic behaviour of subsystem fluctuations provides a test of fluctuation–dissipation relations far from equilibrium and allows the accurate determination of equilibrium transport coefficients using far-from-equilibrium quantum dynamics.

DOI: 10.1038/s41567-024-02611-z

Source: https://www.nature.com/articles/s41567-024-02611-z