# The onset of nanoscale dissipation in superfluid He-4 at zero temperature: the role of vortex shedding and cavitation

## TL;DR

This paper investigates the mechanisms of dissipation in superfluid helium-4 at zero temperature, highlighting vortex shedding and cavitation as critical phenomena, with implications for understanding superfluid dynamics and related quantum fluids.

## Contribution

It provides a detailed theoretical analysis of nanoscale dissipation mechanisms in superfluid helium-4, emphasizing vortex-antivortex pairs and cavitation, extending understanding to self-bound quantum fluids.

## Key findings

- Vortex-antivortex pair shedding triggers dissipation.
- Cavitation occurs in the wake of moving nanoscopic cylinders.
- Dissipation mechanisms are relevant to all self-bound superfluids.

## Abstract

Two-dimensional flow past an infinitely long cylinder of nanoscopic radius in superfluid He-4 at zero temperature is studied by time-dependent density functional theory. The calculations reveal two distinct critical phenomena for the onset of dissipation: 1) vortex-antivortex pair shedding from the periphery of the moving cylinder and 2) appearance of cavitation in the wake, which possesses similar geometry as observed experimentally for fast moving micrometer-scale particles in superfluid He-4. Vortex pairs with the same circulation are occasionally emitted in the form of dimers, which constitute the building blocks for the Benard-von Karman vortex street structure observed in classical turbulent fluids and Bose-Einstein condensates. The cavitation induced dissipation mechanism should be common to all superfluids that are self-bound and have a finite surface tension, which include the recently discovered self-bound droplets in ultracold Bose gases.