Coexistence of Quantum and Classical Flows in Quantum Turbulence in TheT=0Limit

Abstract

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.

Vortex Thermometry for Turbulent Two-Dimensional Fluids

“…Despite this, many recent theoretical works involving superfluid Bose-Einstein condensates (BECs) have suggested that largescale, same-sign Onsager vortex clusters play an important role in 2D quantum turbulence [8][9][10][11][12][13][14][15][16][17]. In superfluids, much of the focus to date has been on decaying-rather than driventurbulence [9,[11][12][13][14][17][18][19][20][21][22][23][24], since this scenario removes the complications of stirring. A variety of concepts have been applied to the problem, including holographic duality [25,26] and nonthermal fixed points [27][28][29].Experimentally, BECs provide unprecedented opportunities to investigate 2D superfluid turbulence due to the high degree of controllability available in these systems.…”

Domain-area distribution anomaly in segregating multicomponent superfluids

“…This suggests that distribution of velocity or vorticity may obey a different scaling law or power law for length scales larger than the average distance l between domain walls. This situation is similar to the hierarchy in quantum turbulence, where the Kolmogorov or semi-classical power law is realized over length scales larger than the average distance between vortex lines and a different power law is expected for smaller length scales [37,38]. In the field of quantum turbulence, the connection regime between the two scaling regimes has also received a lot of attention and should be discussed further qualitatively here.…”

Phenomenology of quantum turbulence in superfluid helium

“…Pure Superfluid Turbulence in He II Driven at Small and Large Scales. Quantitative data on steady-state and decaying pure superfluid He II turbulence have been obtained by Golov and coworkers (34)(35)(36). They injected negative ions into the experimental ‡ Although the energy spectrum beyond ℓ Q has not yet been measured, a hint of possible k −3 scaling at high k appears in the Andreev reflection data (figure 13 in ref.…”