A Deterministic and Storable Single-Photon Source Based on Quantum   Memory
  A single photon source is realized with a cold atomic ensemble ($^{87}$Rb atoms). In the experiment, single photons, which is initially stored in an atomic quantum memory generated by Raman scattering of a laser pulse, can be emitted deterministically at a time-delay in control. It is shown that production rate of single photons can be enhanced by a feedback circuit considerably while the single-photon quality is conserved. Thus our present single-photon source is well suitable for future large-scale realization of quantum communication and linear optical quantum computation. 
Shuai Chen, Yu-Ao Chen, Thorsten Strassel, Zhen-Sheng Yuan, Bo Zhao,   J\"org Schmiedmayer, Jian-Wei Pan