The appearance of the two-photon strong-coupling states is analyzed in atomic vs. semiconductor quantum-dot microcavities. An identical excitation mechanism explains phenomena observed in photon-correlation measurements.
It is shown that spectrally resolved photon-statistics measurements of the resonance fluorescence from realistic semiconductor quantum-dot systems allow for high contrast identification of the two-photon strong-coupling states. Using a microscopic theory, the second-rung resonance of Jaynes-Cummings ladder is analyzed and optimum excitation conditions are determined. The computed photon-statistics spectrum displays gigantic, experimentally robust resonances at the energetic positions of the second-rung emission.
We study the light‐matter interaction of a single semiconductor quantum dot in a microcavity. Excitation‐dependent effects, like dephasing and Coulomb screening lead to a transition from excitonic emission to contributions from multi‐exciton states as the pump is increased. During this transition, the system passes from strong to weak coupling, the photon‐emission changes from sub‐poissonian to coherent emission via bunching, and the output intensity follows an s‐shaped curve typically seen in many‐emitter systems. These effects have also been observed experimentally and explained in terms of an atomic model that also accounts for a background contribution of other emitter. Here we give an alternative interpretation based on the semiconductor nature of the single quantum‐dot emitter.
Resonance fluorescence equations are derived and solved for strong-coupling semiconductor quantum-dot systems using a fully quantized multimode theory and a cluster-expansion approach. A reduced model is developed to explain the origin of autocorrelation and cross-correlation resonances in the two-photon emission spectrum of the fluorescent light. These resonances are traced back to the two-photon strong-coupling states of Jaynes-Cummings ladder. The accuracy of the reduced model is verified via numerical solution of the resonance fluorescence equations. The analysis reveals the direct relation between the squeezed-light emission and the strong-coupling states in optically excited semiconductor systems.