  In a circuit quantum eletrodynamic system, a chain of N qubits
inhomogeneously coupled to a cavity field forms a mesoscopic quasi-lattice,
which is characterized by its degree of deformation from a normal lattice. This
deformation is a function of the relative spacing, that is the ratio of the
qubit spacing to the cavity wavelength. A polariton mode arise in the
quasi-lattice as the dressed mode of the lattice excitation by the cavity
photon. We show that the transition probability of the polariton mode is either
enhanced or decreased compared to that of a single qubit by the deformation,
giving a selective spontaneous radiation spectrum. Further, unlike a
microscopic lattice with large-N limit and nearly zero relative spacing, the
polariton in the quasi-lattice has uneven decay rate over the relative spacing.
We show that this unevenness coincides with the cooperative emission effect
expected from the superradiance model, where alternative excitations in the
qubits of the lattice result in maximum decay.
