The exact solution for a problem of $N$ identical two-level molecules interacting through a dipole coupling with a single-mode quantized radiation field at resonance is given. Approximate expressions for the eigenvectors and eigenvalues for the ground and low-lying excited states, as well as the most highly excited states, are developed and compared with the exact results.

• Received 8 December 1967

DOI:https://doi.org/10.1103/PhysRev.170.379