Photon Blockade in the Ultrastrong Coupling Regime

A. Ridolfo, M. Leib, S. Savasta, M. J. Hartmann
2012 Physical Review Letters  
We explore photon coincidence counting statistics in the ultrastrong-coupling regime where the atom-cavity coupling rate becomes comparable to the cavity resonance frequency. In this regime usual normal order correlation functions fail to describe the output photon statistics. By expressing the electric-field operator in the cavity-emitter dressed basis we are able to propose correlation functions that are valid for arbitrary degrees of light-matter interaction. Our results show that the
more » ... how that the standard photon blockade scenario is significantly modified for ultrastrong coupling. We observe parametric processes even for two-level emitters and temporal oscillations of intensity correlation functions at a frequency given by the ultrastrong photon emitter coupling. These effects can be traced back to the presence of two-photon cascade decays induced by counter-rotating interaction terms.
doi:10.1103/physrevlett.109.193602 pmid:23215383 fatcat:wv6dornjejglhhvc7j6zpybsri