Electromagnetic pulse propagation in a quantum metamaterial - artificial, globally quantum coherent optical medium - is numerically simulated. We show that for the quantum metamaterials based on superconducting quantum bits, initialized in an easily
reachable factorized state, lasing in microwave range is triggered, accompanied by the chaotization of qubit states and generation of higher harmonics. These effects may provide a tool for characterization and optimization of quantum metamaterial prototypes.
