Single-atom switching in photonic crystals - art. no. 033801

We describe the role of first non-Markovian corrections to resonance fluore scence in photonic crystals, using a perturbative expansion of the Heisenbe rg equations of motion in powers of die atom-field reservoir coupling,,stre ngth. Non-Markovian effects arise from the rapid variation of the photonic density of states with frequency. Our method recaptures the physics of the photon-atom bound state in the presence of a full photonic band cap, For th e anisotropic three-dimensional photonic band gap, it predicts remarkable f eatures in the resonance fluorescence, such as atomic population inversion and switching behavior in a two-level atom for moderate values of the appli ed laser field. The magnitude of the switching effect depends sensitively o n the external laser intensity and its detuning frequency from the atomic t ransition. The robustness of this effect against nonradiative decay and dep hasing mechanisms is also investigated.