近日，意大利特伦托大学的A. Recati&G. Lamporesi及其研究团队取得一项新进展。经过不懈努力，他们证实铁磁超流体中通过气泡形成的假真空衰变过程。相关研究成果已于2024年1月22日在国际知名学术期刊《自然—物理学》上发表。
该研究团队通过实验观察了孤立相干耦合原子超流体中的气泡成核，并使用数值模拟来支持他们的观察结果。实验结果与基于瞬子理论的解析公式之间的一致性，证实了他们对衰变过程的物理理解，进一步证实了相干耦合原子超流体作为研究非平衡量子场现象的理想平台。
据悉，亚稳态源于一个状态的有限寿命，当一个较低能量的构型是可用的，但只能通过隧穿通过能量势垒。它在许多自然情况下都可以观察到，包括在化学过程和电子场电离中。在经典多体系统中，亚稳态在一级相变中自然出现。一个典型的例子是过冷蒸汽。量子场论和量子多体系统的扩展在统计物理、蛋白质折叠和宇宙学领域引起了极大的兴趣，其中热和量子涨落有望通过空间局域气泡的概率成核触发从亚稳态（假真空）到基态（真真空）的相变。然而，长期以来通过气泡成核估计亚稳场弛豫速率的理论进展尚未得到实验验证。
附：英文原文
Title: False vacuum decay via bubble formation in ferromagnetic superfluids
Author: Zenesini, A., Berti, A., Cominotti, R., Rogora, C., Moss, I. G., Billam, T. P., Carusotto, I., Lamporesi, G., Recati, A., Ferrari, G.
Issue&Volume: 2024-01-22
Abstract: Metastability stems from the finite lifetime of a state when a lower-energy configuration is available but only by tunnelling through an energy barrier. It is observed in many natural situations, including in chemical processes and in electron field ionization. In classical many-body systems, metastability naturally emerges in the presence of a first-order phase transition. A prototypical example is a supercooled vapour. The extension to quantum field theory and quantum many-body systems has attracted significant interest in the context of statistical physics, protein folding and cosmology, for which thermal and quantum fluctuations are expected to trigger the transition from the metastable state (false vacuum) to the ground state (true vacuum) through the probabilistic nucleation of spatially localized bubbles. However, the long-standing theoretical progress in estimating the relaxation rate of the metastable field through bubble nucleation has not been validated experimentally. Here we experimentally observe bubble nucleation in isolated and coherently coupled atomic superfluids, and we support our observations with numerical simulations. The agreement between our observations and an analytic formula based on instanton theory confirms our physical understanding of the decay process and promotes coherently coupled atomic superfluids as an ideal platform to investigate out-of-equilibrium quantum field phenomena.
DOI: 10.1038/s41567-023-02345-4
Source: https://www.nature.com/articles/s41567-023-02345-4