# Tuning across Universalities with a Driven Open Condensate

## TL;DR

This paper demonstrates how tuning the driving strength in a driven-dissipative polariton system can switch between equilibrium-like superfluid, KPZ phase, and disordered vortex phases, revealing rich non-equilibrium physics.

## Contribution

It shows that simple tuning of the driving process can control the phase behavior of a polariton condensate, connecting equilibrium and non-equilibrium universality classes.

## Key findings

- Changing pump strength alters spatial anisotropy and phase scaling regimes.
- The system can exhibit BKT superfluid, KPZ phase, or vortex-driven disordered phases.
- Finite-size analysis suggests these phases are experimentally observable.

## Abstract

Driven-dissipative systems in two dimensions can differ substantially from their equilibrium counterparts. In particular, a dramatic loss of off-diagonal algebraic order and superfluidity has been predicted to occur due to the interplay between coherent dynamics and external drive and dissipation in the thermodynamic limit. We show here that the order adopted by the system can be substantially altered by a simple, experimentally viable, tuning of the driving process. More precisely, by considering the long-wavelength phase dynamics of a polariton quantum fluid in the optical parametric oscillator regime, we demonstrate that simply changing the strength of the pumping mechanism in an appropriate parameter range can substantially alter the level of effective spatial anisotropy induced by the driving laser, and move the system into distinct scaling regimes. These include: (i) the classic algebraically ordered superfluid below the Berezinskii-Kosterlitz-Thouless (BKT) transition, as in equilibrium; (ii) the non-equilibrium, long-wave-length fluctuation dominated Kardar-Parisi-Zhang (KPZ) phase; and the two associated topological defect dominated disordered phases caused by proliferation of (iii) entropic BKT vortex-antivortex pairs or (iv) repelling vortices in the KPZ phase. Further, by analysing the renormalization group flow in a finite system, we examine the length scales associated with these phases, and assess their observability in current experimental conditions.