We investigate the dynamics of bosonic atoms in elongated Josephson junctions. We find that these systems are characterized by an intrinsic coupling between the Josephson mode of macroscopic quantum tunneling and the sound modes. This coupling of Josephson and sound modes gives rise to a damped and stochastic Langevin dynamics for the Josephson degree of freedom. From a microscopic Lagrangian, we deduce and investigate the damping coefficient and the stochastic noise, which includes thermal and quantum fluctuations. Finally, we study the time evolution of relative-phase and population-imbalance fluctuations of the Josephson mode and their oscillating thermalization to equilibrium.

中文翻译：

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细长玻色约瑟夫森结的耗散和波动

我们研究了拉长约瑟夫森结中玻色子原子的动力学。我们发现这些系统的特点是宏观量子隧穿的约瑟夫森模式和声音模式之间的内在耦合。约瑟夫森和声音模式的这种耦合产生了约瑟夫森自由度的阻尼和随机朗之万动力学。从微观拉格朗日函数中，我们推导出并研究了阻尼系数和随机噪声，其中包括热和量子涨落。最后，我们研究了约瑟夫森模式的相对相位和种群不平衡波动的时间演化及其振荡热化到平衡。