From EIT photon correlations to Raman anti-correlations in coherently   prepared Rb vapor
  We have experimentally observed switching between photon-photon correlations (bunching) and anti-correlations (anti-bunching) between two orthogonally polarized laser beams in an EIT configuration in Rb vapor. The bunching and anti-bunching sswitching occurs at a specific magnetic field strength. 
Vladimir A. Sautenkov, Yuri V. Rostovtsev, and Marlan O. Scully