Experiments on Turbulence in the Pure Quantum Limit

纯量子极限下的湍流实验

• 批准号: EP/D072107/1
• 负责人: Viktor Tsepelin
• 金额: $ 44.72万
• 依托单位: Lancaster University
• 依托单位国家: 英国
• 项目类别: Fellowship
• 财政年份: 2006
• 资助国家: 英国
• 起止时间: 2006 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=EP%2FD072107%2F1
• 关键词: Experiments; Turbulence; Pure; Quantum; Limit

As Richard Feynman stated it Turbulence is the last great unsolved problem of classical physics . Despite being observed at all length scales from the subnuclear to the cosmological, turbulence is one of the least understood phenomena. Turbulent motion impacts on the behaviour of cytoplasm in cells, on the atmosphere, on the oceans, aviation, hydraulics, industrial processing, even on the simple process of water running out of the bath. Despite its ubiquity, physicists have great difficulty in describing and studying the constantly changing mix of eddies that constitute turbulent flow. We see turbulence everywhere but our understanding of it is still very rudimentary. This proposal aims to further our understanding of turbulence in general by addressing the simpler problem of turbulence in pure quantum fluids. We approach the elucidation of turbulence by starting with the most ideal simple model system possible, a superfluid. Although superfluids are widely known for their ability to flow without dissipation, they still form turbulent flow patterns when sufficiently agitated. In a superfluid, the atoms are constrained to move according to the dictates of quantum mechanics since in the superfluid component all the constituent atoms are in the same quantum mechanical state. The crucial point here is that while vortices in a conventional fluid have infinite variability, in a superfluid the circulation is quantized and all the vortices are identical. Quantum turbulence is the sum total of a random tangle of these similar quantized vortex lines.Clearly, the key to investigating quantum turbulence is how to detect the vorticity and measure the distribution and evolution of a turbulent tangle. Despite requiring temperatures well below 1 mK, it turns out that superfluid 3He is most suitable for this purpose. At low enough temperatures, where the normal fluid component is negligible, we have essentially pure quantum turbulence with virtually no frictional dissipation. These are absolute ideal conditions for studying turbulence. The proposed research programmes aims to address the following problems. While we can create turbulence in superfluid 3He, we first need to determine the absolute line densities of the vortex tangle to gain a quantitative description to work with. Secondly, we want to investigate the decay processes of quantum turbulence to contrast the decay with that of classical turbulence, as well as that of high temperature superfluid turbulence. Thirdly, we need to understand the homogeneity of turbulence generated by a vibrating grid resonator, since turbulence decays in time but also can disperse in space and we need to distinguish between the two processes. Finally we want to measure the energy stored in turbulence by following decay of a quantum tangle in a black-body radiator. If we can achieve these goals we will be much further on the road of understanding quantum turbulence.

正如理查德·费曼所说，湍流是经典物理学最后一个未解决的大问题。尽管在从亚核到宇宙的所有尺度上都可以观察到湍流，但湍流是最不为人所知的现象之一。湍流运动对细胞中细胞质的行为、大气、海洋、航空、水力学、工业加工，甚至对水从浴缸中流出的简单过程都有影响。尽管它无处不在，物理学家在描述和研究构成湍流的不断变化的漩涡混合物时有很大的困难。我们到处都能看到湍流，但我们对它的理解仍然非常初级。这个提议的目的是通过解决纯量子流体中的湍流这个更简单的问题来进一步理解湍流。我们从可能的最理想的简单模型系统--超流体出发，来解释湍流。尽管超流体以其无耗散流动的能力而广为人知，但当充分搅拌时，它们仍然形成湍流模式。在超流体中，原子被约束为根据量子力学的指令运动，因为在超流体成分中，所有组成原子都处于相同的量子力学状态。这里的关键点是，虽然传统流体中的涡旋具有无限的可变性，但在超流体中，循环是量子化的，所有的涡旋都是相同的。量子湍流是这些相似的量子化涡旋线的随机纠缠的总和，显然，研究量子湍流的关键是如何检测涡旋和测量湍流纠缠的分布和演化。尽管需要远低于1 mK的温度，但事实证明超流体3 He最适合此目的。在足够低的温度下，正常的流体成分可以忽略不计，我们基本上有纯粹的量子湍流，几乎没有摩擦耗散。这是研究湍流的绝对理想条件。拟议的研究方案旨在解决以下问题。虽然我们可以在超流3 He中创建湍流，但我们首先需要确定涡旋缠结的绝对线密度，以获得定量描述。其次，我们研究了量子湍流的衰减过程，并与经典湍流以及高温超流湍流的衰减过程进行了对比。第三，我们需要了解振动网格谐振器产生的湍流的均匀性，因为湍流在时间上衰减，但也可以在空间上分散，我们需要区分这两个过程。最后，我们想通过跟踪黑体辐射器中量子纠缠的衰变来测量湍流中储存的能量。如果我们能够实现这些目标，我们将在理解量子湍流的道路上走得更远。

项目成果

Direct measurement of the energy dissipated by quantum turbulence

• DOI: 10.1038/nphys1963
• 发表时间: 2011-06-01
• 期刊: NATURE PHYSICS
• 影响因子: 19.6
• 作者: Bradley, D. I.;Fisher, S. N.;Tsepelin, V.
• 通讯作者: Tsepelin, V.

Visualizing Pure Quantum Turbulence in Superfluid 3He: Andreev Reflection and its Spectral Properties.

• DOI: 10.1103/physrevlett.115.015302
• 发表时间: 2015-03
• 期刊: Physical review letters
• 影响因子: 8.6
• 作者: A. Baggaley;V. Tsepelin;C. Barenghi;S. Fisher;G. Pickett;Y. Sergeev;N. Suramlishvili

Fundamental dissipation due to bound fermions in the zero-temperature limit.

• DOI: 10.1038/s41467-020-18499-1
• 发表时间: 2020-09-21
• 期刊: Nature communications
• 影响因子: 16.6
• 作者: Autti S;Ahlstrom SL;Haley RP;Jennings A;Pickett GR;Poole M;Schanen R;Soldatov AA;Tsepelin V;Vonka J;Wilcox T;Woods AJ;Zmeev DE
• 通讯作者: Zmeev DE

Plastic Properties of Solid 4He Probed by a Moving Wire: Viscoelastic and Stochastic Behavior Under High Stress

通过移动导线探测固体 4He 的塑性特性：高应力下的粘弹性和随机行为

• DOI: 10.1007/s10909-013-0922-6
• 发表时间: 2013
• 期刊: Journal of Low Temperature Physics
• 影响因子: 2
• 作者: Ahlstrom S

Turbulent drag on a low-frequency vibrating grid in superfluid 4 He at very low temperatures

极低温度下超流体 4 He 中低频振动网格上的湍流阻力

• DOI: 10.1103/physrevb.85.224533
• 发表时间: 2012
• 期刊: Physical Review B
• 影响因子: 3.7
• 作者: Bradley D