Cooperativity of a few quantum emitters in a single-mode cavity
Résumé
We theoretically investigate the emission properties of a single-mode cavity coupled to a mesoscopic number of incoherently pumped quantum emitters. We propose an operational measure for the medium cooperativity, valid both in the bad- and in the good-cavity regimes. We show that the opposite regimes of subradiance and super-radiance correspond to negative and positive cooperativity, respectively. The lasing regime is shown to be characterized by non-negative cooperativity. In the bad-cavity regime we show that the cooperativity defines the transitions from subradiance to super-radiance. In the good-cavity regime it helps to define the lasing threshold, also providing distinguishable signatures indicating the lasing regime. Increasing the quality factor of the cavity mode induces a crossover from the solely super-radiant to the lasing regime. Furthermore, we verify that lasing is manifested in a wide range of positive cooperative behavior, showing that stimulated emission and super-radiance can coexist. The robustness of the cooperativity is studied with respect to experimental imperfections, such as inhomogeneous broadening and pure dephasing.
Domaines
Physique Quantique [quant-ph]
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