发表机构
Joint Quantum Institute, National Institute of Standards and Technology, and University of Maryland; National Institute of Standards and Technology（联合量子研究所、美国国家标准与技术研究院和马里兰大学; 美国国家标准与技术研究院）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
实验研究淬灭后不可混溶二维玻色-爱因斯坦凝聚体界面，发现涟漪子形成长寿命预热态，高动量模式快速平衡而低动量模式保持高温，归因于运动学隔离。
AI 中文摘要
预热态——长寿命的准平衡构型——出现在广泛的物理系统中，这些系统表现出快速退相或重构，随后缓慢弛豫至热平衡。我们实验研究了不可混溶的二维玻色-爱因斯坦凝聚体（BECs）之间的一维界面；在淬灭之后，界面毛细波（涟漪子）迅速弛豫到一个长寿命的预热态，其特征是能量持续非均分，令人联想到经典的费米-帕斯塔-乌拉姆-青果问题。我们直接测量了界面高度剖面随时间的演化，识别了单个涟漪子模式的贡献，并发现尽管它们的单个振幅呈热分布，但它们并不处于热平衡——高动量模式迅速与二维BEC的体声子模式达到平衡，而较低动量模式则保持在升高的温度下，为整个系统形成长寿命的预热构型。我们将此归因于运动学隔离：在我们的超冷温度系统中，缺乏能量和动量守恒的弛豫过程。
英文摘要
Prethermal states--long-lived quasi-equilibrium configurations--occur in a wide range of physical systems that exhibit fast dephasing or reconfiguration followed by slow relaxation towards thermal equilibrium. We experimentally studied the 1D interface between immiscible 2D Bose-Einstein condensates (BECs); following a quench, the interfacial capillary waves (ripplons) quickly relaxed into a long-lived prethermal state characterized by a persistent non-equipartition of energy, evoking the classic Fermi-Pasta-Ulam-Tsingou problem. We directly measured the interface's height profile as it evolved in time, identified the contribution of individual ripplon modes, and find that, though their individual amplitudes are thermally distributed, they are not in thermal equilibrium--high-momentum modes rapidly equilibrated with the bulk phonon modes of the 2D BEC, while lower momentum modes remained at elevated temperatures, forming a long-lived prethermal configuration for the whole system. We attribute this to kinematic isolation: the absence of energy- and momentum-conserving relaxation processes in our system at ultracold temperature.
Comments5 pages main text (4 figures) + 5 pages SM (3 figures)
