Quantum optics with interacting polaritons

Recent theoretical and experimental investigations evidencing quantum optical effects in semiconductor microcavities are reported. In particular the results of an experiment that probes polariton quantum correlations by exploiting quantum complementarity are described. In this experiment, it has been shown that polaritons in two distinct idler modes interfere if and only if they share the same signal mode so that which-way information cannot be gathered, according to Bohr’s quantum complementarity principle. The experimental results prove the existence of polariton pair correlations that store the which-way information. This interpretation is confirmed by a theoretical analysis of the measured interference visibility in terms of quantum Langevin equations. The devised experimental scheme employs two frequencydegenerate mutually-coherent pump modes. It is shown that this kind of two-pump parametric schemes can be exploited to realize a number of interesting tasks as the emission of polarization-entangled cavitypolariton states and the coherent control and trapping of parametric amplification in SMCs