近日，韩国首尔大学的Y. Shin及其研究团队取得一项新进展。经过不懈努力，他们揭示原子费米超流体中的普适Kibble-Zurek定标关系。相关研究成果已于2024年7月29日在国际知名学术期刊《自然—物理学》上发表。

该研究团队报道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Kibble-Zurek定标关系。他们使用温度和相互作用强度作为两个独立的控制参数来探究超流体相变。研究发现，在两种不同的淬火参数下，凝聚态形成的微观物理特性存在显著差异，凝聚态形成的时间尺度相差两个数量级。然而，不论系统经历相变的热力学方向如何，观察到的Kibble-Zurek指数均约为0.68，与理论预测高度一致。此项工作通过实验验证了液氦的理论推测，即液氦与强相互作用的费米气体属于同一普适类。

据悉，Kibble-Zurek机制是描述对称破缺相变中拓扑缺陷形成和扩展的理论框架。它最初的概念是超流氦。该理论预测，量子漩涡的数量与系统通过λ跃迁的速率之间应存在幂律关系，然而，在超流体系统的实验中证明这种效应难以捉摸。

附：英文原文

Title: Universal Kibble–Zurek scaling in an atomic Fermi superfluid

Author: Lee, Kyuhwan, Kim, Sol, Kim, Taehoon, Shin, Y.

Issue&Volume: 2024-07-29

Abstract: 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.

DOI: 10.1038/s41567-024-02592-z

Source: https://www.nature.com/articles/s41567-024-02592-z