PREPARATION OF NONCLASSICAL FIELD STATES BY RESONANCE FLUORESCENCE IN PHOTONIC BAND STRUCTURES

We analyze the near-resonant interaction between a two-level atom with resonance frequency in a photonic band gap and a local-defect field mode with initially thermal or Poissonian photon statistics. Whereas spontaneous decay is forbidden in this case, atomic states dressed by the defect field can decay via coupling to the mode continuum outside the band gap. Remarkably, the resulting non-Markovian cascade of dressed states transitions can lead to the accumulation of nearly all of the initial photon-number distribution in a single Fock state, upon measuring the excitation of the atom emerging from the structure. Under certain conditions, such a measurement can yield a correlated combination of two adjacent Fock states, which reflects the initial coherence in either the atom or the field. Another striking coherence effect is the non-decaying oscillation (as a function of interaction time) exhibited by Fock-state populations prepared by measuring the final atomic state.