# New perspectives on superfluidity in resonantly--driven polariton fluids

## TL;DR

This paper investigates superfluidity and related phenomena in driven polariton fluids using the Gross-Pitaevskii framework, revealing complex behaviors like soliton formation, instabilities, and the influence of disorder, with implications for experimental validation.

## Contribution

It provides new insights into non-equilibrium polariton superfluidity, highlighting the effects of continuous pumping, disorder, and non-stationary behaviors within a driven-dissipative model.

## Key findings

- Superfluid flow around defects is disrupted, showing a crossover to soliton-like perturbations.
- Weak dependence of flow properties on pump parameters in one-dimensional regimes.
- Disorder and incoherent reservoirs induce non-stationary vortex dynamics.

## Abstract

In this paper we discuss, within the Gross--Pitaevskii framework, superfluidity, soliton nucleation, and instabilities in a non-equilibrium polariton fluid injected by a spatially localized and continuous-wave coherent pump and flowing against a defect located outside the pump spot. In contrast to equilibrium condensates, the steady-state solutions of the driven-dissipative equations in this specific geometry hardly show a clean superfluid flow around the defect and rather feature a crossover from shallow to deep soliton-like perturbation. This is explained in terms of the properties of one-dimensional flows, in particular their weak dependence on the pump parameters and their rapid transition to a super-sonic regime under the effect of the quantum pressure; such a highly nonlinear behaviour calls for quantitative experimental tests of the underlying Gross--Pitaevskii equation. The role of disorder and of a incoherent reservoir in inducing non-stationary behaviours with moving vortices is also highlighted.