Quantum storage of single-photon and two-photon Fock states with an all-optical quantum memory

Quantum memories are a crucial element towards efficient quantum protocols. In the continuous variables domain, such memories need to have near unity efficiencies. Moreover, one needs to store complex quantum states exhibiting negative Wigner functions after storage. We report the implementation of an all optical quantum memory: the storage of single and two-photon Fock states with high fidelities has been realized. The Wigner functions of the reconstructed states shows negativity after $\sim 0.75~\mu s$ and $\sim 0.61~\mu s$ respectively for the single-photon and two-photon Fock states. This is, to our knowledge, the first demonstration of the storage of non-Gaussian states with more than one photon, representing a key step towards hybrid quantum protocols.