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arXiv:2410.00588 · Physical Review A

Quantum correlations, mixed states, and bistability at the onset of lasing

F. Papoff, Mark Anthony Carroll, Gian Luca Lippi, Gian‐Luca Oppo, Giampaolo D’Alessandro

Published Jan 7, 2025• 4 citations
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Abstract

We derive a model for a single-mode laser that includes all two-particle quantum correlations between photons and electrons. In contrast to the predictions of semiclassical models, we find that lasing takes place in the presence of quantum bistability between a nonlasing and a nonclassical coherent state. The coherent state is characterized by a central frequency and a finite linewidth and emerges with finite amplitude from a saddle-node bifurcation together with an unstable coherent state. Hence coherent emission in nanolasers originates through a mixing of lasing and nonlasing states. In the limit of a macrolaser with a large number of emitters and nonresonant modes, the laser threshold approaches the prediction of the semiclassical theory, but with the important difference that lasing can be achieved only in the presence of finite-size perturbations.

DOI
10.1103/physreva.111.l011501

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We compare a novel quantum mechanical model of lasers, which includes all two-particle correlations, with the Coherent-Incoherent Model (CIM), where truncation eliminates these effects. Numerical results for the simple case of identical single-electron quantum dots are presented for two cases: only the laser mode is coupled to the quantum dots; the coupling is extended to non-resonant modes. We find coexistence between non-lasing and lasing states, together with a minimum number of photons required to initiate the laser action. The correlations introduce a non-zero variance in the field, which is otherwise strictly zero in the absence of interparticle correlations.
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