Walmsley P M, Golov A I
School of Physics and Astronomy, The University of Manchester, Manchester M13 9PL, United Kingdom.
Phys Rev Lett. 2017 Mar 31;118(13):134501. doi: 10.1103/PhysRevLett.118.134501. Epub 2017 Mar 29.
Tangles of a quantized vortex line of initial density L(0)∼6×10^{3} cm^{-2} and a variable amplitude of fluctuations of flow velocity U(0) at the largest length scale are generated in superfluid ^{4}He at T=0.17 K, and their free decay L(t) is measured. If U(0) is small, the excess random component of the vortex line length first decays as L∝t^{-1} until it becomes comparable with the structured component responsible for the classical velocity field, and the decay changes to L∝t^{-3/2}. The latter regime always ultimately prevails, provided the classical description of U holds. A quantitative model of coexisting cascades of quantum and classical energies describes all regimes of the decay.
在T = 0.17 K的超流⁴He中产生了初始密度L(0) ∼ 6×10³ cm⁻²且在最大长度尺度上流速涨落幅度可变U(0)的量子化涡旋线缠结，并测量了它们的自由衰减L(t)。如果U(0)较小，涡旋线长度的过量随机分量首先按L∝t⁻¹衰减，直到它变得与负责经典速度场的结构化分量相当，然后衰减变为L∝t⁻³/²。只要U的经典描述成立，后一种情况最终总是占主导。量子和经典能量共存级联的定量模型描述了衰减的所有情况。
