Quantum Networking with Diamond and Lithium Niobate Integrated Photonics

Abstract

The realization of quantum networks capable of distributing quantum information over kilometer scale distances is key to maximizing the potential of quantum information technology. Implementing this technology requires both the ability to generate remote entanglement between quantum memory nodes, requiring an efficient spin-photon interface, and the ability to efficiently scale the classical optical control and multiplexing optics within a given node. In this work, we develop integrated photonics platforms in diamond and thin film lithium niobate to address both of these issues. Together, these platforms provide the necessary ingredients to create large scale quantum networking technology. For the quantum network nodes, we extend previous results combining diamond nanophotonic resonators with the silicon-vacancy defect as a quantum networking platform. We demonstrate, for the first time, quantum entanglement between SiV quantum memories across 35km in a deployed fiber network. We also develop additional functionalities within the SiV platform including the incorporation of deterministic strain to increase defect yield and deterministic single photon generation with the SiV. In order to enable the scalable control and multiplexing of individual SiV centers necessary for realizing practical quantum network nodes, we develop a state-of-the-art electro-optics platform operating at visible wavelengths using thin film lithium niobate. We develop an understanding of fabrication induced losses at visible wavelengths in the platform and a variety of key devices in the platform including high-bandwidth, low-drive voltage amplitude and phase modulators, as well as high-efficiency off chip couplers. Utilizing this platform we perform ultra-high efficiency electro-optic frequency shifting, achieving a 15 GHz frequency shift with over 50% efficiency. Finally, using our measured device performance, we discuss and model how these devices can effectively multiplex SiV-based quantum nodes. Thus through these two platforms we have demonstrated the necessary ingredients to realize large-scale quantum network nodes.