Universal behaviour often emerges in the low-energy equilibrium physics of quantum many-body systems, despite their microscopic differences. Recently, there has been a growing interest in studying the far-from-equilibrium dynamics of quantum many-body systems. Such dynamics usually involve highly excited states beyond the traditional low-energy theory description. Whether universality can also emerge in such non-equilibrium dynamics is the subject of current research. Here, we report the experimental observation of universal dynamics by monitoring the spin depolarization process in a solid-state nuclear magnetic resonance system, described by an ensemble of randomly interacting spins. The spin depolarization can be related to temporal spin–spin correlation functions at high temperatures. We discover that these correlation functions obey a universal functional form. This finding helps us identify the dominant interacting processes in the spin depolarization dynamics that lead to universality. Our observation demonstrates the existence of universality even in non-equilibrium dynamics at high temperatures, thereby complementing the well-established universality in low-energy physics.

尽管量子多体系统的低能平衡物理学存在微观差异，但普遍行为经常出现在量子多体系统的低能平衡物理学中。最近，人们对研究量子多体系统的远非平衡动力学越来越感兴趣。这种动力学通常涉及超出传统低能理论描述的高激发态。普遍性是否也能在这种非平衡动态中出现是当前研究的主题。在这里，我们通过监测固态核磁共振系统中的自旋去极化过程来报告对普遍动力学的实验观察，该系统由随机相互作用的自旋集合描述。自旋去极化可能与高温下的时间自旋-自旋相关函数有关。我们发现这些相关函数服从一种通用的函数形式。这一发现有助于我们确定导致普遍性的自旋去极化动力学中的主要相互作用过程。我们的观察证明了即使在高温下的非平衡动力学中也存在普遍性，从而补充了低能物理学中公认的普遍性。