Onsager-Kraichnan Condensation in Decaying Two-Dimensional Quantum Turbulence
Onsager-Kraichnan Condensation in Decaying Two-Dimensional Quantum Turbulence
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DOI：
10.1103/physrevlett.112.145301
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发表时间：
2014-04-11
影响因子：
8.6
通讯作者：
Bradley, A. S.
中科院分区：
文献类型：
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作者：
Billam, T. P.;Reeves, M. T.;Bradley, A. S.
尽管Onsager的点涡模型作为二维经典湍流的统计描述非常突出，但该模型在现实超流体中的第一性原理发展仍然是一个开放的问题。在这里，我们开发了一个由齐次二维Gross-Pitaevskii方程（GPE）描述的量子漩涡系统到点涡模型的映射，使涡旋微正则系综的蒙特卡罗采样成为可能。我们用这种方法研究了二维超流体中的全范围涡旋状态，从正温度下的涡旋偶极子气体到负温度状态，表现出宏观涡旋聚集和动能凝聚，我们称之为Onsager-Kraichnan凝聚（OKC）。阻尼GPE模拟表明，这种OKC状态可以动态地出现，通过将小簇聚集成巨大的OKC簇，作为可压缩、有限温度超流体中衰变的二维量子湍流的最终状态。这些统计平衡态应该可以在原子玻色-爱因斯坦凝聚实验中得到。
Despite the prominence of Onsager's point-vortex model as a statistical description of 2D classical turbulence, a first-principles development of the model for a realistic superfluid has remained an open problem. Here we develop a mapping of a system of quantum vortices described by the homogeneous 2D Gross-Pitaevskii equation (GPE) to the point-vortex model, enabling Monte Carlo sampling of the vortex microcanonical ensemble. We use this approach to survey the full range of vortex states in a 2D superfluid, from the vortex-dipole gas at positive temperature to negative-temperature states exhibiting both macroscopic vortex clustering and kinetic energy condensation, which we term an Onsager-Kraichnan condensate (OKC). Damped GPE simulations reveal that such OKC states can emerge dynamically, via aggregation of small-scale clusters into giant OKC clusters, as the end states of decaying 2D quantum turbulence in a compressible, finite-temperature superfluid. These statistical equilibrium states should be accessible in atomic Bose-Einstein condensate experiments.