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Probing Quantum Turbulence in ^{4}He by Quantum Evaporation Measurements
Ivan Amelio1,2, Davide Emilio Galli1, Luciano Reatto1
1Dipartimento di Fisica "Aldo Pontremoli", Università degli Studi di Milano, via Celoria 16, I-20133 Milano, Italy.
Physical Review Letters
|July 21, 2018
Summary
Superfluid helium-4 (⁴He) vortex lines exhibit density modulations, not simple rarefactions. This suggests vortex reconnection generates nonthermal rotons, detectable via quantum evaporation.
Area of Science:
- Quantum fluid dynamics
- Condensed matter physics
Background:
- Vortex lines in superfluids are complex structures.
- Previous models did not fully capture the density profile of superfluid vortices.
Purpose of the Study:
- To investigate the density profile of vortex lines in superfluid helium-4 (⁴He).
- To explore the role of excitations in vortex dynamics and quantum turbulence.
Main Methods:
- Theoretical analysis of superfluid ⁴He.
- Modeling vortex density modulation as a cylindrical wave packet.
- Estimating quantum evaporation rates.
Main Results:
- Vortex line density profiles are modulations, not simple rarefactions, due to correlations and backflow.
- Rotons with positive group velocity dominate these modulations.
- Vortex reconnection is predicted to generate nonthermal rotons.
Conclusions:
- Vortex density modulations are sustained by virtual roton excitations.
- Quantum turbulence in ⁴He is a source of nonthermal rotons.
- Quantum evaporation measurements can verify these findings and provide insights into turbulence decay.
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