Smooth vortex precession in superfluid<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msup><mml:mrow /><mml:mrow><mml:mn>4</mml:mn></mml:mrow></mml:msup></mml:mrow><mml:mi mathvariant="normal">He</mml:mi></mml:math>

Hough, Loren E.; Donev, L. A. K.; Zieve, R. J.

doi:10.1103/physrevb.65.024511

Cited by 9 publications

(12 citation statements)

References 23 publications

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“…First, from the theoretical point of view it will provide an easier way to describe the role of the particle mass in the vortex dynamics and its effect on vortex excitations. On the other hand, such setting is similar to recent experiments that study the nanowire formation by the coalescence of gold nanofragments on quantum vortices [31] or experiments with vibrating wires inside quantum vortices in superfluid 3 He and 4 He [32,33]. Finally, Fig.…”

Section: Motion Of Particles Trapped By Quantum Vortexsupporting

confidence: 83%

How trapped particles interact with and sample superfluid vortex excitations

Giuriato

Krstulovic²,

Nazarenko

2020

Phys. Rev. Research

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Particles have been used for more than a decade to visualize and study the dynamics of quantum vortices in superfluid helium. In this work we study how the dynamics of a collection of particles set inside a vortex reflects the motion of the vortex. We use a self-consistent model based on the Gross-Pitaevskii equation coupled with classical particle dynamics. We find that each particle oscillates with a natural frequency proportional to the number of vortices attached to it. We then study the dynamics of an array of particles trapped in a quantum vortex and use particle trajectories to measure the frequency spectrum of the vortex excitations. Surprisingly, due to the discreetness of the array, the vortex excitations measured by the particles exhibit bands, gaps, and Brillouin zones, analogous to the ones of electrons moving in crystals. We then establish a mathematical analogy where vortex excitations play the role of electrons and particles that of the potential barriers constituting the crystal. We find that the height of the effective potential barriers is proportional to the particle mass and the frequency of the incoming waves. We conclude that large-scale vortex excitations could be in principle directly measured by particles and novel physics could emerge from particle-vortex interaction.

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Section: Motion Of Particles Trapped By Quantum Vortexsupporting

confidence: 83%

How trapped particles interact with and sample superfluid vortex excitations

Giuriato

Krstulovic²,

Nazarenko

2020

Phys. Rev. Research

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“…We do not take these as evidence of a non-quantum vortex trapped along the entire wire; rather, they indicate that a quantized vortex covers only a fraction of the wire and hence has a reduced effect on its vibration frequencies. The clean and reproducible signatures we find in several situations [15,18] confirm this interpretation. As noted above, we can use the frequency splitting of the vibrational modes as an instantaneous measurement of the length of wire covered by the vortex.…”

Section: Methodssupporting

confidence: 83%

“…In the thin half of the cell, the much steeper slope corresponds to energy loss of 47×10 −12 erg/s. Previous experimental [15] and computational [23] work has found that changes in energy loss and precession period are related, with an increase in dissipation corresponding to a longer period. However, that relationship holds for precession within a cell of fixed diameter, not for the change in precession period with cell diameter that we observe here.…”

Section: Dissipationmentioning

confidence: 93%

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Energy loss from a moving vortex in superfluid helium

2012

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We present measurements on both energy loss and pinning for a vortex terminating on the curved surface of a cylindrical container. We vary surface roughness, cell diameter, fluid velocity, and temperature. Although energy loss and pinning both arise from interactions between the vortex and the surface, their dependences on the experimental parameters differ, suggesting that different mechanisms govern the two effects. We propose that the energy loss stems from reconnections with a mesh of microscopic vortices that covers the cell wall, while pinning is dominated by other influences such as the local fluid velocity.

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“…Conveniently, direct comparison between superfluid hydrodynamics calculations and experiment becomes possible. In several cases such simulations accurately describe non-trivial experimental behaviors [5,6].Here we compare vortex pinning in experiment and calculation, finding discrepancies that may indicate a need to modify the computational treatment of surfaces. Our measurements track a single vortex in superfluid helium interacting with a macroscopic bump.…”

mentioning

confidence: 88%

Vortex pinning by surface geometry in superfluid helium

Neumann

Zieve

2014

Phys. Rev. B

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We present measurements of how a single vortex line in superfluid helium interacts with a macroscopic bump on the chamber wall. At a general level our measurements confirm computational work on vortex pinning by a hemispherical bump, but not all the details agree. Rather than observing a unique pin location, we find that a given applied velocity field can support pinning at multiple sites along the bump, both near its apex and near its edge. We also find that pinning is less favorable than expected. A vortex can pass near or even traverse the bump itself with or without pinning, depending on its path of approach to the bump.Vortex methods have appeared for decades in computational work on classical fluids in both two and three dimensions [1,2]. They track the vorticity, which is the curl of the velocity field, rather than the velocity itself. The velocity can then be extracted using the Biot-Savart law. Vortex methods apply naturally to situations where the vorticity is concentrated in particular regions of the fluid; applications range from simulating trailing vortices of aircraft [1] to doing time updates of the computer graphics in video games [3]. A main benefit is that evaluating the velocity field does not require tracking a fine grid of points.A complication for vortex methods is the treatment of the vortex cores, which in classical fluids change shape and size as vortex lines bend and move. Using a fixed size for the vortex cores, while more straightforward in conception and implementation, is valid only when the core size is small compared to all other length scales, including the local radius of curvature of the vortex and the spacing between the computational points along the vortex [4]. This restriction does apply naturally in superfluid 4 He, where the experimentally measured core radius is about 1.3Å, small enough to be ignored on typical computational and experimental length scales. Conveniently, direct comparison between superfluid hydrodynamics calculations and experiment becomes possible. In several cases such simulations accurately describe non-trivial experimental behaviors [5,6].Here we compare vortex pinning in experiment and calculation, finding discrepancies that may indicate a need to modify the computational treatment of surfaces. Our measurements track a single vortex in superfluid helium interacting with a macroscopic bump. We compare to the computational work of Schwarz [7], for a hemispherical bump on an otherwise flat wall. Schwarz uses a flow field that far from the bump is uniform and parallel to the wall. He finds that if the vortex is swept into the vicinity of the bump, the bump can capture and pin the vortex [7]. If the flow velocity is large the vortex continues to move, but for sufficiently low velocities it remains at the bump. The calculation uses no explicit pinning forces; rather, the stationary configuration comes about entirely from the vortex settling into an arrangement where the net velocity vanishes along its core. For a given flow velocity, the pinned vortex term...

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Smooth vortex precession in superfluid4He

Cited by 9 publications

References 23 publications

How trapped particles interact with and sample superfluid vortex excitations

How trapped particles interact with and sample superfluid vortex excitations

Energy loss from a moving vortex in superfluid helium

Vortex pinning by surface geometry in superfluid helium

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