Optical parametric oscillator with quantum memory for quantum repeaters

We consider preparing entangled states between single photons and quantum memory by combining two-photon source based on spontaneous parametric down-conversion and multiatomic quantum memory in a common resonator. The scheme allows one to minimize the losses while the photon to be stored is propagating from the source to the quantum memory and avoids the need to synchronize their operating wavelength. In this respect, the scheme is analogous to the cavity-enhanced embedded memory within Duan-Lukin-Cirac-Zoller approach, but it remains possible to generate a second photon at the wavelength of the fiber optic communication channel and use various multiplexing methods inherent in multiatomic quantum memory.