Critical dynamics of a two-dimensional superfluid near a nonthermal fixed point
Critical dynamics of a two-dimensional superfluid near a nonthermal fixed point
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DOI：
10.1103/physreva.86.013624
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发表时间：
2012-04
影响因子：
2.9
通讯作者：
Jan Schole;B. Nowak;T. Gasenzer
中科院分区：
文献类型：
--
作者：
Jan Schole;B. Nowak;T. Gasenzer
在二维空间中研究了远离平衡态的超冷玻色气体的临界动力学。超流体湍流是通过使平衡状态在接近零的温度下淬火而产生的。而不是立即再热化，系统接近亚稳态瞬态，其特征在于作为一个非热固定点。一个重点是设置在涡密度和涡反涡的相关性，其特征的演变对非热不动点和最终（准）冷凝的偏离。两个不同的幂律制度中的涡密度衰减被发现和讨论的涡绑定-解绑定过渡和动力学描述的涡散射。一个可能的关系衰减湍流在经典流体中指出。通过比较的结果，二维玻色气体的平衡研究，一个直观的理解的位置的非热固定点在一个约化的相空间。
Critical dynamics of an ultracold Bose gas far from equilibrium is studied in two spatial dimensions. Superfluid turbulence is created by quenching the equilibrium state close to zero temperature. Instead of immediately re-thermalizing, the system approaches a meta-stable transient state, characterized as a non-thermal fixed point. A focus is set on the vortex density and vortex-antivortex correlations which characterize the evolution towards the non-thermal fixed point and the departure to final (quasi-)condensation. Two distinct power-law regimes in the vortex-density decay are found and discussed in terms of a vortex binding-unbinding transition and a kinetic description of vortex scattering. A possible relation to decaying turbulence in classical fluids is pointed out. By comparing the results to equilibrium studies of a two-dimensional Bose gas, an intuitive understanding of the location of the non-thermal fixed point in a reduced phase space is developed.