# Interactions and scattering of quantum vortices in a polariton fluid

## TL;DR

This paper investigates the dynamics and interactions of quantum vortices in a polariton fluid within a microcavity, revealing how nonlinearity and density gradients influence vortex behavior and scattering events.

## Contribution

It provides new insights into vortex interactions at the particle level in open quantum systems, including vortex splitting and tunable scattering phenomena.

## Key findings

- Vortices exhibit rotational dynamics driven by nonlinearity and phase gradients.
- Composite spin-vortex molecules can split into half-vortices due to vorticity seeding.
- Close-proximity vortices undergo scattering-like events described by an effective potential.

## Abstract

Quantum vortices, the quantized version of classical vortices, play a prominent role in superfluid and superconductor phase transitions. However, their exploration at a particle level in open quantum systems has gained considerable attention only recently. Here we study vortex pair interactions in a resonant polariton fluid created in a solid-state microcavity. By tracking the vortices on picosecond time scales, we reveal the role of nonlinearity, as well as of density and phase gradients, in driving their rotational dynamics. Such effects are also responsible for the split of composite spin-vortex molecules into elementary half-vortices, when seeding opposite vorticity between the two spinorial components. Remarkably, we also observe that vortices placed in close proximity experience a pull-push scenario leading to unusual scattering-like events that can be described by a tunable effective potential. Understanding vortex interactions can be useful in quantum hydrodynamics and in the development of vortex-based lattices, gyroscopes, and logic devices.