Quantum computing with multidimensional continuous-variable cluster states in a scalable photonic platform

Quantum computing is a disruptive paradigm widely believed to be capable of solving classically intractable problems. However, the route toward full-scale quantum computers is obstructed by immense challenges associated with the scalability of the platform, the connectivity of qubits, and the required fidelity of various components. One-way quantum computing is an appealing approach that shifts the burden from high-fidelity quantum gates and quantum memories to the generation of high-quality entangled resource states and high fidelity measurements. Cluster states are an important ingredient for one-way quantum computing, and a compact, portable, and mass producible platform for large-scale cluster states will be essential for the widespread deployment of one-way quantum computing. Here, we bridge two distinct fields-Kerr microcombs and continuous-variable (CV) quantum information-to formulate a one-way quantum computing architecture based on programmable large-scale CV cluster states. Our scheme can accommodate hundreds of simultaneously addressable entangled optical modes multiplexed in the frequency domain and an unlimited number of sequentially addressable entangled optical modes in the time domain. One-dimensional, two-dimensional, and three-dimensional CV cluster states can be deterministically produced. When combined with a source of non-Gaussian Gottesman-Kitaev-Preskill qubits, such cluster states enable universal quantum computation via homoyne detection and feedforward. We note cluster states of at least three dimensions are required for fault-tolerant one-way quantum computing with known error-correction strategies. This platform can be readily implemented with silicon photonics, opening a promising avenue for quantum computing on a large scale.