Artificial atoms in microcavities

An artificial atom can be built up by means of nanostructures of either semiconductors or superconductors. They can be embedded in solid-state optical cavities in order to get strong coupling between the artificial atom excitations and the discrete spectrum of electromagnetic modes. We present here an overview of the dynamics of such a system for the cases of two- and four-level artificial atoms in the presence of an incoherent continuous pumping and the emission of cavity and leaky modes. From a master equation for the density matrix and the quantum regression theorem, one obtains the correlation functions required to compute both the spectrum and the characteristics of the emission of pairs and single photons. A quantum regime appears for low pumping and large rate of emission of cavity photons. In this regime, a large polarization entanglement visibility could be obtained in a two beams experiment with different linear polarizations.