Noisy metamolecule: strong narrowing of fluorescence line

We consider a metamolecule consisting of a bosonic mode correlated with a two-level system (TLS): it can be, for example, a plasmonic mode interacting with a quantum dot. We focus on the parameter range where all the correlations are strong and of the same order. The interaction between the bosonic mode is correlated with the TLS, external coherent drive, and dissipation. Quantum Monte Carlo simulations show that the fluorescence of this system at dissipation is larger than the driving amplitude and shows a strong (by the order of magnitude) narrowing of its spectral line. This effect may be related to kind of a quantum stochastic resonance. We show that the fluorescence corresponds to the finite domain over the coherent drive with sharp, low threshold, and that the Wigner function splits.