Large-scale integrated quantum photonics with artificial atoms

Abstract

The construction of large, controllable quantum systems is a formidable task in quantum science and technology. In the context of quantum networks, single emitters in diamond have emerged as leading quantum bits that combine long coherence times with efficient optical interfaces. Despite their potential manufacturability, such solidstate qubits have been limited to small-scale quantum network demonstrations due to their low system efficiencies, deteriorated properties in devices, and low yields. To address these challenges, we report the development of a nanophotonic platform in diamond for the efficient control and routing of photons. In particular, we describe the fabrication and coupling of qubits to diamond parabolic reflectors, single-mode waveguides and photonic crystal resonators. We then demonstrate the large-scale heterogeneous integration of diamond waveguide-coupled qubits with photonic circuits in another material system. This hybrid quantum chip architecture enables the combination of coherent qubits in diamond with low-loss active photonics in aluminum nitride or silicon nitride. This modularity also circumvents the low device yields associated with monolithic chips, enabling here a 128-channel, qubit-integrated photonic chip with frequency tunability and high optical coherence. Finally, we describe new qubit flavors in diamond that offer potentially long spin coherence times at higher operational temperatures. As an outlook, we discuss ongoing efforts that combine the advances in this thesis towards the construction of a quantum repeater microchip.