Quantum storage and manipulation of heralded single photons in atomic memories based on electromagnetically induced transparency

We demonstrate the storage and manipulation of heralded single photons generated from a cavity-enhanced spontaneous parametric down-conversion (SPDC) source in the atomic quantum memory based on electromagnetically induced transparency. We show that nonclassical correlations are preserved between the heralding and the retrieved photons after storage process. By varying the intensity of the coupling field during retrieval process, we further demonstrate that the waveform or bandwidth of the single photons can be manipulated and the reduction of the nonclassical correlation between the photon pairs can be compensated. Our SPDC photon pairs are generated in a single pair of longitudinal cavity modes, which not only reduces the experimental complexity arising from external filtering but also increases the useful photon generation rate. Our results can be scaled up with ease and thus lay the foundation for future realization of large-scale applications in quantum information processing.