Spectral properties of coupled cavity arrays in one dimension are
investigated by means of the variational cluster approach. Coupled cavity
arrays consist of two distinct "particles," namely, photons and atomiclike
excitations. Spectral functions are evaluated and discussed for both particle
types. In addition, densities of states, momentum distributions and spatial
correlation functions are presented. Based on this information, polariton
"quasiparticles" are introduced as appropriate, wave vector and filling
dependent linear combinations of photon and atomiclike particles. Spectral
functions and densities of states are evaluated for the polariton
quasiparticles, and the weights of their components are analyzed.Comment: 17 pages, 16 figures, version as publishe