Raman adiabatic transfer of quantum optical states in atomic media

We present a method for transforming quantum optical states by means of an adiabatic process comparable to STIRAP. We consider a quantum light pulse propagating through an atomic ensemble of a lambda-type energy level configuration with multiple excited states. Starting with an EIT condition to ensure a loss-free propagation of the initial quantum field, we slowly change the EIT control fields so the associated dark state is converted to another two-photon resonance. The input quantum state of light will then reemerge from the sample carried by a pulse of another frequency. This scheme is useful for the routing of quantum and classical communication. It may also be applicable for quantum-optical state engineering, such as splitting of optical states into different frequency modes or “fusing” optical modes together.