  We investigate the steady state phase diagram of two-component driven open
condensates in one dimension. We identify a miscible-immiscible transition
which is predominantly driven by gapped density fluctuations and occurs upon
increasing the inter-component inelastic coupling. Below the transition in the
miscible phase, we find the effective long wavelength dynamics to be described
by a two-component Kardar-Parisi-Zhang (KPZ) equation that belongs to the
nonequilibrium universality class of the one-dimensional single-component KPZ
equation at generic choices of parameters. Our results are relevant for
different experimental realizations for two-component driven open condensates
in exciton-polariton systems.
