Hybrid atom — rare-earth ion quantum interfaces and network nodes

Future global quantum networks will merge heterogeneous quantum systems to simultaneously perform multiple tasks, namely, reliably store, process, and transmit quantum information as well as distribute entanglement. The functionality of such networks relies crucially on coherent interfaces between disparate nodes and telecom photons which connect distant nodes through low-loss optical fibers. We propose a modular hybrid network architecture consisting of a matching pair of telecom nodes with GHz frequency differences to circumvent losses due to quantum frequency conversion processes. On one side, a single atom coupled to a nanophotonic crystal cavity serves as our processing qubit node, generating high-fidelity atom-telecom photon entanglement at fast rates through time-bin photonic qubits. On the other side, a rare-earth ion-doped crystal serves as our memory qubit node, where the inhomogeneous broadening allows broadband storage and spectral multiplexing for multiple time-bin photonic qubits, creating entanglement between the two nodes. In this talk, we will present our results identifying the mode-matching conditions between a rubidium vapor cell and an erbium-doped crystal, where the former serves as a telecom single photon source via phase-matched four-wave mixing. We will also discuss our experimental progress towards establishing the atom-nanophotonic system as the processor node and multimode storage in the memory node.