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arXiv 2603.28587quant-ph
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Gaussian Unitary Ensemble Hamiltonians的平均平衡时间

Average Equilibration Time for Gaussian Unitary Ensemble Hamiltonians

University of Malta(马耳他大学);Technische Universität Wien(维也纳工业大学);Trinity College Dublin(都柏林三一学院);Università degli Studi di Palermo(巴勒莫大学);Austrian Academy of Sciences(奥地利科学院)

Emanuel Schwarzhans, Alessandro Candeloro, Felix C. Binder, Maximilian P. E. Lock, Pharnam Bakhshinezhad

AI总结:

本文研究了GUE系统中平衡时间的平均值,发现其与初始态和观测量无关,且随系统规模减小,在热力学极限下趋于零,表明随机矩阵理论无法完全描述真实混沌系统。

摘要:

理解封闭量子系统中平衡时间对于表征其向平衡态演化至关重要。在这一背景下,混沌多体系统是典型例子:它们根据简态热化假说预期热化,并表现出由随机矩阵理论(RMT)良好描述的谱特性。尽管RMT成功捕捉谱相关性,但其提供平衡时间尺度的定量预测能力仍鲜有探索。本文通过将平衡视为退相干的框架,研究RMT内的平衡问题,聚焦于其哈密顿量来自GUE的封闭系统。我们推导出一个近似表达式,近似计算GUE的平均平衡时间,并显示其与初始态和观测量选择无关,这是GUE旋转不变性的结果。数值模拟验证了我们的解析表达式,并证明我们的近似与GUE的真实平均平衡时间高度一致。我们发现平衡时间随系统规模减小,并在热力学极限下消失。这一不合理的结论表明,真实混沌多体系统的平衡时间尺度必须由随机矩阵集合未捕捉的物理特征主导——特别是GUE。

英文摘要:

Understanding equilibration times in closed quantum systems is essential for characterising their approach to equilibrium. Chaotic many-body systems are paradigmatic in this context: they are expected to thermalise according to the eigenstate thermalisation hypothesis and exhibit spectral properties well described by random matrix theory (RMT). While RMT successfully captures spectral correlations, its ability to provide quantitative predictions for equilibration timescales has remained largely unexplored. Here, we study equilibration within RMT using the framework of equilibration as dephasing, focusing on closed systems whose Hamiltonians are drawn from the Gaussian unitary ensemble (GUE). We derive an analytical expression that approximates the average equilibration time of the GUE and show that it is independent of both the initial state and the choice of observable, a consequence of the rotational invariance of the GUE. Numerical simulations confirm our analytical expression and demonstrate that our approximation is in close agreement with the true average equilibration time of the GUE. We find that the equilibration time decreases with system size and vanishes in the thermodynamic limit. This unphysical result indicates that the true equilibration timescale of realistic chaotic many-body systems must be dominated by physical features not captured by random matrix ensembles -- the GUE in particular.

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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