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Photon Blockade in the Ultrastrong Coupling Regime

2012; American Physical Society; Volume: 109; Issue: 19 Linguagem: Inglês

10.1103/physrevlett.109.193602

1092-0145

A. Ridolfo, Martin Leib, Salvatore Savasta, Michael J. Hartmann,

Quantum optics and atomic interactions

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 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 counterrotating interaction terms.