Quantum vortices leave a macroscopic signature in the normal fluid

Fuente: arXiv
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Main Authors: Galantucci, Luca, Krstulovic, Giorgio, Barenghi, Carlo F
Format: Preprint
Published: 2025
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_version_ 1866911244920815616
author Galantucci, Luca
Krstulovic, Giorgio
Barenghi, Carlo F
author_facet Galantucci, Luca
Krstulovic, Giorgio
Barenghi, Carlo F
contents Recent work has highlighted the remarkable properties of quantum turbulence in superfluid helium II, consisting of a disordered tangle of quantised vortex lines which interact with each other and reconnect when they collide. According to Landau's two-fluid theory, these vortex lines move in a surrounding of thermal excitations called the normal fluid. Until now, the normal fluid has often been considered a passive background which simply provides the vortex lines with a mechanism for dissipating their kinetic energy into heat. Using a model which fully takes into account the two-way interaction between the vortex lines and the normal fluid, here we show numerically that each vortex line creates a macroscopic wake in the normal fluid that can be larger than the average distance between vortex lines; this is surprising, given the microscopic size of the superfluid vortex cores which induce these wakes. We show that in heat transfer experiments, the flow of the normal fluid can therefore be described as the superposition of an imposed uniform flow and wakes generated by the vortex lines, leading to non-classical statistics of the normal fluid velocity. We also argue that this first evidence of independent fluid structures in the thermal excitations postulated by Landau may be at the root of recent, unaccounted for, experimental findings.
format Preprint
id arxiv_https___arxiv_org_abs_2501_08309
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Quantum vortices leave a macroscopic signature in the normal fluid
Galantucci, Luca
Krstulovic, Giorgio
Barenghi, Carlo F
Fluid Dynamics
Other Condensed Matter
Quantum Gases
Quantum Physics
Recent work has highlighted the remarkable properties of quantum turbulence in superfluid helium II, consisting of a disordered tangle of quantised vortex lines which interact with each other and reconnect when they collide. According to Landau's two-fluid theory, these vortex lines move in a surrounding of thermal excitations called the normal fluid. Until now, the normal fluid has often been considered a passive background which simply provides the vortex lines with a mechanism for dissipating their kinetic energy into heat. Using a model which fully takes into account the two-way interaction between the vortex lines and the normal fluid, here we show numerically that each vortex line creates a macroscopic wake in the normal fluid that can be larger than the average distance between vortex lines; this is surprising, given the microscopic size of the superfluid vortex cores which induce these wakes. We show that in heat transfer experiments, the flow of the normal fluid can therefore be described as the superposition of an imposed uniform flow and wakes generated by the vortex lines, leading to non-classical statistics of the normal fluid velocity. We also argue that this first evidence of independent fluid structures in the thermal excitations postulated by Landau may be at the root of recent, unaccounted for, experimental findings.
title Quantum vortices leave a macroscopic signature in the normal fluid
topic Fluid Dynamics
Other Condensed Matter
Quantum Gases
Quantum Physics
url https://arxiv.org/abs/2501.08309