Visualisation of quantised vortex reconnection as enabled by laser ablation

TL;DR

This paper demonstrates a novel laser ablation method to visualize and study the interaction between dense silicon nanoparticles and quantised vortices in superfluid helium, including vortex reconnection phenomena.

Contribution

It provides experimental evidence of impurity-vortex attraction and visualizes vortex reconnection using laser ablation-produced silicon nanoparticles.

Findings

Silicon nanoparticles form filament-like structures along vortex cores.

Observed vortex reconnection events match dynamical scaling laws.

Laser ablation enables new visualization of impurity-vortex interactions.

Abstract

Impurity injection into superfluid helium is a simple yet unique method with diverse applications, including high-precision spectroscopy, quantum computing, nano/micro materialsynthesis, and flow visualisation. Quantised vortices are believed to play a major role in the interaction between superfluid helium and light impurities. However, the basic principle governing the interaction is still controversial for dense materials such as semiconductor and metal impurities. Herein, we provide experimental evidence of the attraction of the dense silicon nanoparticles to the quantised vortex cores. We prepared the silicon nanoparticles via in-situ laser ablation. Following laser ablation, we observed that the silicon nanoparticles formed curved-filament-like structures, indicative of quantised vortex cores. We also observed that two accidentally intersecting quantised vortices exchanged their parts, a phenomenon called quantised vortex reconnection. This behaviour closely matches the dynamical scaling of reconnections. Our results provide a new method for visualising and studying impurity-quantised vortex interactions.