Scattering and bound states of two polaritons in an array of coupled   cavities
  We develop an analytical approach for calculating the scattering and bound states of two polaritons in a one-dimensional (1D) infinite array of coupled cavities, with each cavity coupled to a two-level system (TLS). In particular, we find that in such a system a contact interaction between two polaritons is induced by the nonlinearity of the Jaynes-Cummigs Hamiltonian. Using our approach we solve the two-polariton problem with zero center-of-mass momentum, and find 1D resonances. Our results are relevant to the transport of two polaritons, and are helpful for the investigation of many-body physics in a dilute gas of polaritons in a 1D cavity array. 
Chuan-zhou Zhu, Shimpei Endo, Pascal Naidon and Peng Zhang
quant-ph cond-mat.other