Single photons made-to-measure

We investigate the efficiency of atom-cavity-based photon-generation schemes to deliver single photons of arbitrary temporal shape. Our model applies to Raman transitions in three-level atoms with one branch of the transition driven by a laser pulse and the other coupled to a cavity mode. For any possible shape of the single-photon wavepacket, we derive an unambiguous analytic expression for the shape of the required driving laser pulse. Furthermore, we discuss the constraints limiting the maximum probability for emitting any desired photon, and use these to estimate upper bounds for the efficiency of the process. The model is not only valid for vacuum-stimulated Raman adiabatic passages (V-STIRAP) in the strong-coupling and bad-cavity regime, but also generally allows the control of the coherence and population flow in any Raman process.