One knob to tune them all: Phase-controlled photon statistics and linewidth in partially pumped atomic ensembles

We study a minimal model of collective light emission from an incoherently driven ensemble of atoms where incoherent drive is applied to only a subset of the atoms and show that both the linewidth and the photon statistics can be controlled within a single framework. In this setting, collective dissipation induces correlations between the pumped and unpumped parts of the system, leading to interference between their emission contributions. By introducing a relative phase between these contributions and tuning the pump rate, we demonstrate that the properties of the emitted light can be varied over a broad range. In particular, the linewidth can be made either independent of system size or scale extensively with it, while the photon statistics can be tuned from antibunched or quantum to bunched. We further show that the role of the relative phase in controlling the interference can alternatively be played by the coherent interaction. By tuning the interaction strength together with the pump rate, one can access the same regimes as in the dissipation-only model. In addition, coherent interactions stabilize regimes of coherent emission with narrow linewidth, reminiscent of superradiant lasing. Our results illustrate how interference in partially driven collective systems provides a flexible mechanism for tailoring both spectral and statistical properties of light.