Blueprint for a Scalable Photonic Fault-Tolerant Quantum Computer*

We present Xanadu's proposal for a scalable and fault-tolerant photonic quantum computer. Central to our architecture are Gottesman-Kitaev-Preskill bosonic qubits and squeezed states of light, stitched together into a qubit cluster state with one time and two spatial dimensions. This proposal for generating and manipulating a 3D resource state for fault-tolerant, measurement-based quantum computation combines state-of-the-art procedures for the preparation of bosonic qubits with the strengths of continuous-variable quantum computation performed using easy-to-generate squeezed states. Moreover, the architecture is based on modular, easy-to-network integrated photonic chips, opening the door to scalable fabrication and operation, which may in turn allow photonics to leap-frog other platforms on the path to a quantum computer with millions of qubits. In addition to overviewing the architecture from Xanadu's blueprint, we discuss subsequent work - including improvements to the stitching component - that significantly facilitate the creation of a useful quantum computer.