Comment on "Thermal, Quantum Antibunching and Lasing Thresholds from Single Emitters to Macroscopic Devices"

TL;DR

This paper critiques a recent model of nanolaser emission, revealing that key terms were omitted, which affected the predicted threshold behavior and the emergence of coherent fields.

Contribution

It identifies missing terms in the existing model, challenging the predicted bifurcation and threshold behavior of nanolasers.

Findings

The original model's bifurcation at finite pump rate is due to omitted terms.

Corrected analysis shows different threshold behavior for nanolasers.

Implications for understanding the transition from thermal to coherent emission.

Abstract

In a recent Letter [Phys. Rev. Lett. 126, 063902 (2021)], M. A. Carroll et al. derived a model to analytically determine regimes of thermal, collective anti-bunching, and laser emission for emitters in a cavity. According to their model, nanolasers exhibit a distinct threshold at which the coherent laser field emerges from a bifurcation at a finite pump rate. The amplitude of this coherent field increases with a further increase in the pump rate. Such a behavior contrasts the usual view of the transition to lasing in single-mode high-$\beta$ nanolasers, according to which strong spontaneous emission into the lasing mode results in a smooth transformation from the thermal state to the coherent state as the pump rate increases. Here, we demonstrate that the authors have ignored important terms in the equations of their model, which caused the bifurcation and the ideally monochromatic field to emerge at a finite pump rate.