Towards integration of optically active defects in silicon photonics

Modular quantum architectures are an encouraging means of reaching the large scales necessary to unlock the potential of quantum technologies. Silicon based spin-photon interfaces are a potent combination for a scalable, modular architecture as they combine the long lived memories of solid state qubits, the long range networking capabilities of photons, and the CMOS compatibility and integrated photonics of silicon. In this work we push forward the understanding of two promising spin-photon interface candidates based in silicon. Firstly, we study the properties of 77Se+ in a natSi host material to measure the coherence properties and couplings to 29Si spins. We identify clock transitions with coherence times more than an order of magnitude longer compared the coherence times measured off the clock transition. The 77Se+ culminates in a presentation of a proposal to utilize a 77Se+-29Si pair system as a spin-photon interface. Secondly, we demonstrate further steps in the integration of the T centre into a silicon-on-insulator system by incorporating ensembles into waveguide devices. We measure sharp homogeneous linewidths for waveguide ensembles and find nearly lifetime-limited homogeneous linewidths in bulk silicon samples. In both environments the T centre's transitions are sufficiently coherent to predict the success of a remote entanglement procedures using currently available silicon photonic cavities. In summary, this work continues paving the path from a qubit candidate to an integrated qubit to a concrete technological solution for both the 77Se+ and T centre spin-photon interfaces.