Devices and Materials for Quantum Network Nodes Based on Rare Earth Ions

Abstract

Future large scale quantum networks will open the door to provably secure communication as well as distributed quantum computing and quantum-enhanced sensing. This Thesis focuses on developing a fundamental element of a long-distance quantum network: a quantum memory that can interface with light at $1.5 \mu$m, the wavelength used for telecommunication networks. This memory is in the form of a single erbium atom embedded in a crystal host. We develop this platform following two main thrusts: engineering devices to interface with these single erbium atoms as well as studying the materials that can be used as a host crystal for the erbium. Toward this first thrust, we leverage mature silicon nanophotonics technology to create an optical interface with single erbium atoms, the first demonstration of its kind. Toward studying new materials, we formulate a framework to identify promising host crystals. We then develop a pipeline to introduce erbium to these crystals and study its optical and magnetic properties. This work has identified several new host crystals for erbium that have not been previously explored for quantum network applications. We then demonstrate improved device performance by making the single ion devices with one of these new host crystals. This sets the groundwork for a promising platform that could be used as the backbone for next-generation quantum networks.