Correlations between uncoupled particles induced by the interaction with different types of light are investigated using a superoperator formalism. We derive compact expressions for the doubly-excited-state distributions of noninteracting multilevel atoms excited by classical laser light, classical stochastic light, and quantum light. We find that the $g_2$ function of the incoming light can be directly related to its ability to induce correlations in the matter. Unlike coherent light, quantum light can induce entanglement between the atoms. The photon coincidence signal created by classical fields may be factorized into a product of single photon counting rates. This is not the case for quantum light.

• Received 22 July 2013

DOI:https://doi.org/10.1103/PhysRevA.89.013830