Cavity QED beyond the Jaynes–Cummings model

Abstract As atom-cavity systems are becoming more sophisticated, the limitations of the Jaynes–Cummings model are becoming more apparent. In this paper, we therefore take a more dynamical approach to the modelling of atom-cavity systems and do not reduce the electromagnetic field inside the resonator to a single mode. Our approach shows that the decay rate $$\Gamma _{\textrm{cav}}$$ of an emitter inside a subwavelength cavity with metallic mirrors can be much larger than its free space decay rate $$\Gamma _{\textrm{free}}$$ due to constructive interference effects of the emitted light. In general, however, we find that $$\Gamma _{\textrm{cav}} = \Gamma _{\textrm{free}}$$ to a very good approximation which might explain why atom-cavity experiments with planar mirrors have not been able to operate in the so-called strong coupling regime.