论文标题
后期子系统的波动
Fluctuations of subsystem entropies at late times
论文作者
论文摘要
我们研究了热化后封闭量子多体系统中子系统熵的波动。使用分析和数字在随机量子电路和哈密顿动力学方面的组合，我们发现此类熵波动的统计数据与经典环境截然不同。例如，在系统热化后不久，在互补子区域的希尔伯特空间的维度中抑制了子区域的熵波动的概率。随着时间的函数，这种抑制变得越来越严格，最终取决于希尔伯特空间维度的指数，直到抑制量饱和的时间很晚。我们还使用结果来估计大时标的罕见波动的总数。我们发现与经典环境相比，“玻尔兹曼大脑”悖论在量子多体系统中大大改善。
We study the fluctuations of subsystem entropies in closed quantum many-body systems after thermalization. Using a combination of analytics and numerics for both random quantum circuits and Hamiltonian dynamics, we find that the statistics of such entropy fluctuations is drastically different than in the classical setting. For instance, shortly after a system thermalizes, the probability of entropy fluctuations for a subregion is suppressed in the dimension of the Hilbert space of the complementary subregion. This suppression becomes increasingly stringent as a function of time, ultimately depending on the exponential of the Hilbert space dimension, until extremely late times when the amount of suppression saturates. We also use our results to estimate the total number of rare fluctuations at large timescales. We find that the "Boltzmann brain" paradox is largely ameliorated in quantum many-body systems, in contrast with the classical setting.
