Towards quantum memory

The implementation of many applications of quantum communication and computation such as quantum repeaters relies on the possibility to reversibly transfer quantum information between photons and atoms. Key properties for such a quantum memory are high recall efficiency and long storage times, and the capacity to store short photonic wavepackets with high fidelity. Our approach towards quantum state storage is based on rare-earth ion doped solid state material (crystalline and amorphous waveguides) at cryogenic temperature, and "controlled reversible inhomogeneous broadening" (CRIB) of a narrow absorption line [1]. Implementation of CRIB relies on the possibility to prepare such an absorption line out of an inhomogeneously broadened medium by means of optical pumping, and to broaden this line in a controlled and reversible way. After an introduction into CRIB, we will present spectroscopic investigations of Thulium doped Lithium Niobate waveguides and silicate fibers, and analyze these novel material candidates in view of the requirements for quantum memory.