The coherent interaction between photons and atoms lays the bases of quantum information science, whose purpose is to open new possibilities for the transmission and the processing of information. It is crucial, for example, for the realization of quantum networks. Here the optical quantum memories are fundamental building blocks as they allow synchronizing the different stages of the quantum processes. The first proof of principle demonstrations of quantum memories were carried out in ensembles of atomic gases, but recently, some solid-state systems have emerged as a promising alternative. More specifically the rare earth ion doped crystals are one of the most interesting candidates.
In this contribution, I will present new strategies to develop quantum devices, as quantum memories  and sources of entangled photons , using Pr3+: YSO crystals. This material has demonstrated very promising properties for light storage, including highly efficient excited state storage of weak coherent states  and long-lived storage of classical images in the time scale of a minute .
Moreover, I will report on the demonstration of a novel platform for quantum light storage based on laser written waveguides in a new writing regime that enables obtaining waveguides with improved confining capabilities compared to previous demonstrations . I will show how, besides the remarkable advantages that this platform offers with respect to other integrated designs, such as the compatibility with fiber cords and the 3D capability, it also opens the way for spatial and frequency multiplexing in quantum storage protocol .
Finally, I will discuss future development of the research on integrated quantum devices based on rare earth doped solids.
1] A. Seri, et al., PRX, 7 021028 (2017)
 K. Kutluer et al, submitted
 M. P. Hedges et al, Nat. 465, 1052 (2010)
 G. Heinze et al, PRL 111, 033601 (2013)
 A. Seri, G. Corrielli, et al, Optica 5 934 (2018)
 A. Seri, D. Lago-Rivera, et al., submitted