Visualization of quantized vortex reconnection enabled by laser ablation

Impurity injection into superfluid helium is a simple and appealing method with diverse applications, including high-precision spectroscopy, quantum computing with surface electrons, nano/micromaterial synthesis, and flow visualization. Quantized vortices play a major role in the interaction between superfluid helium and light impurities. However, the basic principle governing this interaction is still unclear for dense (high mass density and refractive index) materials, such as semiconductor and metal impurities. Here, we provide experimental evidence of the dense silicon nanoparticle attraction to the quantized 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 quantized vortex cores. We also observed that two accidentally intersecting quantized vortices exchanged their parts, a phenomenon called quantized vortex reconnection. This behavior closely matches the dynamical scaling of reconnections. Our results provide a previously unexplored method for visualizing and studying impurity-quantized vortex interactions.

Dynamics of the Vortex-Particle Complexes Bound to the Free Surface of Superfluid Helium

We present an experimental and theoretical study of the 2D dynamics of electrically charged nanoparticles trapped under a free surface of superfluid helium in a static vertical electric field. We focus on the dynamics of particles driven by the interaction with quantized vortices terminating at the free surface. We identify two types of particle trajectories and the associated vortex structures: vertical linear vortices pinned at the bottom of the container and half-ring vortices traveling along the free surface of the liquid.

Drift mechanism of the metal nanowires formation in liquid helium

It is shown theoretically that the mechanism of the rapid coagulation of metal nanospheres into a nanowire in a quantum vortex proposed by E. B. Gordon et al. (Low Temp. Phys., 2010, 36, 590) could not be realized, due to the enormous heat release expelling the nanospheres from the vortex.

Taylor cone and electrospraying at a free surface of superfluid helium charged from below

Electrically charged metallic micro- and nanoparticles are trapped under a free surface of superfluid He in a vertical static electric field. We observe a static deformation of the charged liquid surface in the form of a Taylor cone and the emission of a charged liquid helium jet (electrospray). Our numeric calculations reproduce the static shape of the cone.