Hybrid atom—rare-earth ion interface for quantum networks

To achieve a quantum network with both processing capabilities and robust storage, it is very appealing to leverage the complementary strengths of different quantum platforms. Coherently interfacing such platforms, however, can be challenging, as it requires wavelength and bandwidth matching, along with conversion to telecom wavelengths for long-distance entanglement distribution. As such, we propose a modular, hybrid quantum network architecture that has both programmability and multi-mode storage, and evades complex frequency conversion techniques by generating and storing entangled photons at telecom. We propose to use an atom array as our processor node, with integrated nanophotonic cavities to generate high-fidelity, high-rate entanglement between atoms and telecom photons. The photons can then be stored in a memory node consisting of a rare-earth ion-doped crystal that allows multiplexed storage. Here we present our results on identifying mode-matching conditions between rubidium atoms and an erbium-doped crystal, along with our experimental progress on coupling atoms to nanophotonics, generating single telecom photons via four-wave mixing in a hot rubidium ensemble, and preparing an atomic frequency comb memory in the crystal.