Tunable single photon source from an atomic quantum memory for storage in a highly excited Rydberg state

Quantum information science and technology critically rely on generation and processing of single photons, the natural carriers of quantum information in this context. The ability to realize strong interactions between single photons would enable new powerful applications like photonic quantum computing or deterministic Bell state measurements [1]. A promising approach to obtain that capability is based on mediating photon-photon interactions via strong Dipole-Dipole interactions, when one photon is stored via electromagnetically induced transparency (EIT) in a Rydberg atom. This, however, requires single photons, which are spectrally compatible with the conditions set by the atomic energy structure and EIT.