The Kibble–Zurek mechanism is a theoretical framework that describes the formation and scaling of topological defects in symmetry-breaking phase transitions. It was originally conceptualized for superfluid helium. The theory predicts that the number of quantum vortices should scale as a power law with the rate at which the system passes through the lambda transition, but demonstrating this effect has been elusive in experiments using superfluid systems. Here, we report the observation of Kibble–Zurek scaling in a homogeneous, strongly interacting Fermi gas undergoing a superfluid phase transition. We investigate the superfluid transition using temperature and interaction strength as two distinct control parameters. The microscopic physics of condensate formation is markedly different for the two quench parameters, as shown by the two orders of magnitude difference in the condensate formation timescale. However, regardless of the thermodynamic direction in which the system passes through a phase transition, the Kibble–Zurek exponent is identically observed to be about 0.68, in good agreement with theoretical predictions. This work experimentally demonstrates the theoretical proposal laid out for liquid helium, which is in the same universality class as strongly interacting Fermi gases.

Kibble-Zurek 机制是一个理论框架，描述对称破缺相变中拓扑缺陷的形成和缩放。它最初的概念是针对超流氦。该理论预测，量子涡旋的数量应与系统通过 lambda 跃迁的速率呈幂律关系，但在使用超流体系统的实验中证明这种效应一直难以捉摸。在这里，我们报告了在经历超流体相变的均匀、强相互作用的费米气体中观察到的基布尔-祖雷克结垢。我们使用温度和相互作用强度作为两个不同的控制参数来研究超流体转变。对于两个淬火参数，冷凝物形成的微观物理现象明显不同，如冷凝物形成时间尺度的两个数量级差异所示。然而，无论系统经历相变的热力学方向如何，Kibble-Zurek 指数都相同地观察到约为 0.68，与理论预测非常一致。这项工作通过实验证明了为液氦提出的理论建议，液氦与强相互作用的费米气体属于同一普适性类别。