Observation of resonant photon blockade at microwave frequencies using correlation function measurements
C. Lang, D. Bozyigit, C. Eichler, L. Steffen, J.M. Fink, A. Abdumalikov, M. Baur, S. Filipp, M. Da Silva, A. Blais, A. Wallraff, Physical Review Letters 106 (2011).