Nanowire formation by gold nano-fragment coalescence on quantized vortices in He II

We demonstrate that laser ablation of a gold target immersed in superfluid and normal fluid helium leads to the formation of elongated gold nano-fragments. In the superfluid phase these nano-fragments aggregate into filaments with extremely large aspect ratios displaying metallic electric conductivity. We attribute this unusual structure to the coalescence of gold particles trapped on quantized vortices. Our observations suggest new ways to visualize the structure of quantized vortex bundles and a new approach for producing centimeter-long metal nanowires.