Networking silicon qubits

Distributed quantum processing over local optical networks is a route to fault-tolerant quantum computing at scale and practical quantum advantage. The performance of modular, networked quantum technologies will, however, be contingent upon the quality of their light-matter interconnects. Silicon colour centres offer optically-coupled spin qubit registers as the basis for quantum networks and distributed quantum computing. Silicon is an ideal platform for commercial quantum technologies: it unites advanced photonics and the microelectronics industry, as well as hosting long-lived spin qubits. The silicon T centre was recently discovered to combine direct telecommunications-band photonic emission, long-coherence electron and nuclear spins 1,2, and proven integration into industry-standard, CMOS-compatible, silicon-on-insulator (SOI) photonic chips at scale. In this talk I present recent advances networking T centres with nanophotonics. We enhance the optical emission rate by an order of magnitude with integrated nanocavities to create coherent optical interfaces. We determine the T centre's hyperfine spin qubit coupling and introduce schemes for operating each T centre as a deterministic four-qubit spin register. T centre devices producing spin-entangled photons can make immediate use of integrated silicon photonic networks boasting low-loss active components, efficient coupling to standard telecommunications fibres, and efficient on-chip photon detectors. These elements may be assembled to create an on-chip spin-photon quantum processor that interfaces with optical fibres for long-range communication over the quantum internet.