Intra-scales energy transfer during the evolution of turbulence in a trapped Bose-Einstein condensate
Intra-scales energy transfer during the evolution of turbulence in a trapped Bose-Einstein condensate
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DOI：
10.1209/0295-5075/130/46001
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发表时间：
2020-05-01
期刊：
影响因子：
1.8
通讯作者：
Bagnato, Vanderlei S.
中科院分区：
文献类型：
--
作者：
Daniel Garcia-Orozco, Arnol;Madeira, Lucas;Bagnato, Vanderlei S.
在湍流现象中，包括超流体中的量子湍流，能量通量从大尺度流向小尺度，形成能量级联。湍流的一个普遍特征是存在一系列尺度，其中能量通量是尺度不变的：这个尺度区间通常被称为惯性区域。这一属性是基础性的，例如，在经典流体的湍流中，它表征了光谱和结构函数等统计特征的行为。在这里，我们表明，在被捕获的玻色-爱因斯坦凝聚体（BEC）中产生的衰变量子湍流中，也可以识别能量通量恒定的动量空间区间。事实上，我们提出了一种使用能谱和连续性方程来测量能量通量的程序。然后使用两种不同的协议确定通量恒定的尺度范围，并且在同一范围内，测量的动量分布与之前的工作一致。成功识别湍流 BEC 中恒定通量的区域体现了这些量子系统中湍流的普遍特征。这些测量为研究俘获原子超流体中的能量守恒和耗散以及与普通流体中发生的相关过程的类比铺平了道路。
In turbulence phenomena, including the quantum turbulence in superfluids, an energy flux flows from large to small length scales, composing a cascade of energy. A universal characteristic of turbulent flows is the existence of a range of scales where the energy flux is scale-invariant: this interval of scales is often referred to as inertial region. This property is fundamental as, for instance, in turbulence of classical fluids it characterizes the behavior of statistical features such as spectra and structure functions. Here we show that also in decaying quantum turbulence generated in trapped Bose-Einstein condensates (BECs), intervals of momentum space where the energy flux is constant can be identified. Indeed, we present a procedure to measure the energy flux using both the energy spectrum and the continuity equation. A range of scales where the flux is constant is then determined employing two distinct protocols and in the same range, the momentum distribution measured is consistent with previous work. The successful identification of a region with constant flux in turbulent BECs is a manifestation of the universal character of turbulence in these quantum systems. These measurements pave the way for studies of energy conservation and dissipation in trapped atomic superfluids, and also analogies with the related processes that take place in ordinary fluids.