A Quantum Computer Architecture Based on Silicon Donor Qubits Coupled by Photons

A comprehensive circuit architecture and a protocol for realizing 3D cluster states through photonic-measurement-based donor-spin-qubit entanglement and readout are described. The basic building blocks and protocol are chosen to be compatible with a fully integrated photonic circuit implementation, using Se⁺ as the photonically coupled matter qubit. The basic operational building blocks of this universal quantum computing machine are local measurements and unitaries, plus an entangling measurement of non-local Pauli operators. By analyzing several sources of error, a theoretical fault-tolerant threshold value is estimated on the order of 1%. Considering the literature where required components have already been realized in integrated silicon circuits, albeit not all on the same chip, this suggests the threshold is within reach.