A Modified Quasi-Classical Analysis to Capture the Effects of Strong Interaction in Open QED Lattices

The role of optical nonlinearity in light propagation through two different 1D open QED lattices is investigated, namely a chain of qubits with direct coupling between the nearest neighbors and a chain of connected resonators to each of which a qubit is side-coupled. Using the more accurate truncated Heisenberg-Langevin equations method, a reduction of light transmission with increasing intensity in these lattices is shown due to effective photon–photon interactions and related photon blockade mediated by nonlinearity in qubits. In contrast to the direct-coupled qubits, a revival in the light transmission is found in the side-coupled qubits at relatively higher intensities due to saturation of qubits by photons. In absence of bulk dissipation, it is found that the standard quasi-classical analysis fails to capture the reduction in light transmission due to effective photon–photon interaction. A systemic method is devised to modify the quasi-classical analysis to give much better results.