Atom-Nanophotonic Quantum Network Node with Direct Telecom Operation

Practical quantum networks designed for long distance operation require the use of telecom photons to mitigate fiber losses. However, many promising qubit candidates do not have ground state telecom transitions. We propose a scheme that overcomes this limitation by strongly coupling atomic qubits to telecom nanophotonic cavities which both provide the efficient light-matter interface necessary for a quantum network node and circumvent the need for frequency conversion by exploiting excited-excited state transitions. Specifically, our scheme creates robust time-bin entanglement between the atomic hyperfine ground states and telecom photons collected via the cavity mode. We show that high fidelity entanglement can be generated with experimentally realistic parameters including cavity coupling strength, finite atomic temperature, and polarization impurity of the addressing lasers due to the nearby dielectric surface.

We will present these results with emphasis on our recent experimental progress towards realizing this network node architecture including fabrication and characterization of high quality factor nanophotonic cavities, coupling to our cavities via free space, and a compact vacuum chamber designed for integration of a photonic chip hosting many nanophotonic devices.