A note on the emission spectrum and trapping states in the Jaynes-Cummings model

The emission of light from an atom represents a fundamental process that provides valuable insights into the atom-light interaction. The Jaynes-Cummings model is one of the simplest fully quantized models to deal with these interactions, allowing for an analytical solution, while exhibiting notable non-trivial effects. We explore new features in the fluorescence emission spectrum for initial "trapping states", which suppress the atomic population inversion. Despite the seemingly dormant activity of the atom, the resulting emission spectra exhibit rich features, and using a dressed-state coordinates formalism, we are able to quantitatively explain the different profiles in the spectrum. We generalize the trapping conditions for non-zero atom-field detuning and also unveil two types of trapping states that lead to spectra with three peaks, in contrast to previously known states: a center peak and one secondary peak on each side. These are a trapping state formed by a Schrödinger cat state with Poissonian statistics (Yurke-Stoler state) and also a different type of "perfect trapping state".