Analyzing the collective emission of a single-photon source based on an ensemble of thermal Rydberg atoms

An ensemble of Rydberg atoms can be excited with lasers such that it evolves into an entangled state with just one collective excitation within the Rydberg blockade radius. The decay of this state leads to the emission of a single, antibunched photon. For a hot vapor of Rubidium atoms in a micro cell we numerically study the feasibility of such a single-photon source under different experimental conditions like the atomic density distribution and the choice of electronic states addressed by the lasers. For the excitation process with three rectangular lasers pulses, we simulate the coherent dynamics of the system in a truncated Hilbert space. We investigate the radiative behavior of the moving Rydberg atoms and optimize the laser pulse sequence accordingly. We find that the collective decay of the single-excitation leads to a fast and directed photon emission. Finally, we analyze the residual double-excitations and find that they do not exhibit these collective decay properties and play only a minor deleterious role.