Storage and retrieval of a single photon emitted by a quantum memory on a highly excited Rydberg state

Strong interaction between two single photons [1], is a long standing and important goal in quantum photonics. This would enable a new regime of nonlinear optics and unlock several applications in quantum information science, including photon-photon gates and deterministic Bell-state measurements for quantum networking. In the context of quantum networks [2], a particularly important case is to achieve strong interaction between single photons from independent photon pairs that can be stored in quantum memories. So far, most of the efforts towards nonlinear effects at the single-photon level have been realized using weak classical input light.