Multi-mode effects in cavity QED based on a one-dimensional cavity array

We present a microscopic model of cavity quantum electrodynamics based on a one-dimensional (1D) coupled cavity array (CCA), where a supercavity (SC) is composed by a segment of the 1D CCA with relatively smaller couplings with the outsides. The single-photon scattering problem for the SC empty or with a two level atom in it is investigated. We obtain the exact theoretical result on the transmission rate for our system, which predicts that the transmission peaks shall appear near the eigenenergies of the SC. Our numerical results further prove that the SC is a well-defined multimode cavity. When a two level atom resonant with the SC locates at the antinode of the resonant mode, the transmission spectrum shows a clear sign of vacuum Rabi splitting as expected. However, when the atom locates at the node of the resonant mode, we observe a deep valley in the transmission peak, which can be explained by the destructive interference of two transmission channels: one is the resonant mode, while the other is arising from the atom coupling with the nonresonance modes. The effect of nonresonance modes on vacuum Rabi splitting is also analyzed.