STRONG-COUPLING QED IN A SPHERE - DEGENERACY EFFECTS

We investigate the resonant interaction of a dipolar j=0 <---->-j=1 an gular-momentum transition with the quantized field in a dielectric sph ere. New features arise account of the degeneracy of atomic levels and field modes with low azimuthal angular momentum, in slightly deformed spheres (oblate spheroids). For TE-mode excitation we obtain the dyna mics of a degenerate Lambda or V configuration with the usual coherent -state collapse and revivals. For TM-mode excitation new behavior is f ound: due to interference between sigma- and pi-polarizsii transitions , which can be controlled by the atomic position and/or dipole orienta tion, coherent-state revivals and the corresponding atom-field energy exchange may be suppressed or delayed.