A nanophotonic device as a quantum network node for atoms in optical tweezers

Abstract

Platforms consisting of neutral atoms individually trapped in arrays of optical tweezers have achieved important milestones in quantum simulation and quantum computation. With access to programmable Rydberg interactions, individual qubit control, long coherence times, and naturally identical qubit transitions, neutral atoms are a promising building-block for the use in future quantum machines. However, they face the same challenge as other quantum platforms in scaling the number of qubits needed to perform algorithms with a provable advantage over classical computers. An avenue toward scaling systems of neutral atoms may be to use a quantum network that connects individual systems to construct a distributed computing architecture. Key to this approach is for the atoms to have access to an efficient optical interface, where the quantum information can be mapped to a single photon and sent across a quantum network. This thesis explores using a nanophotonic crystal cavity to act as this interface. With our device, we have demonstrated high-cooperativity coupling of two atoms to the photonic mode, generated entanglement at the device using a projective measurement, and coherently transported an entangled pair of atoms away from the device. Furthermore, we have taken the first steps toward integrating this device with Rydberg-excited atoms. We have found that the nanoscale dielectric device creates a point-charge electric field that minimally perturbs ground-Rydberg qubit coherence at distances greater than 200 microns. Using the Rydberg blockade effect, we have created an entangled pair of atoms to perform entanglement-assisted sensing of the electric field to better understand its control. Overall, these experiments show how this nanophotonic device is a promising candidate to use as an optical interface for a Rydberg atom-based quantum computing node.