How trapped particles interact with and sample superfluid vortex excitations

Abstract

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 exhibits 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.

arXiv comment13 pages, 7 figures

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Cited by in corpus (9)

• Making ghost vortices visible in two-component Bose-Einstein condensates
• Eulerian and Lagrangian second-order statistics of superfluid ${}^4$He grid turbulence
• Active and finite-size particles in decaying quantum turbulence at low temperature
• Quantum vortex reconnections mediated by trapped particles
• Stochastic motion of finite-size immiscible impurities in a dilute quantum fluid at finite temperature
• Kelvin waves in nonequilibrium universal dynamics of relativistic scalar field theories
• Kelvin waves, mutual friction, and fluctuations in the Gross-Pitaevskii model
• Stokes drift and impurity transport in a quantum fluid
• Quantum vortex driven Kelvin wave in the thermal background of superfluid helium