2020/12/31 by Christopher Chamberland, Kyungjoo Noh, Patricio Arrangoiz-Arriola +13 · 2 citations
Physics and Astronomy · #quant-ph
paper · pdf · doi:10.1103/prxquantum.3.010329
published as PRX Quantum 3, 010329 (2022) · 117 pages (main text 32 pages), 62 figures, 15 tables. Comments welcome! V2 adds additional appendices and conforms to journal specifications
arxiv created 2022/01/27 · arxiv updated 2022/02/25
We present a comprehensive architectural analysis for a proposed fault-tolerant quantum computer based on cat codes concatenated with outer quantum error-correcting codes. For the physical hardware, we propose a system of acoustic resonators coupled to superconducting circuits with a two-dimensional layout. Using estimated physical parameters for the hardware, we perform a detailed error analysis of measurements and gates, including CNOT and Toffoli gates. Having built a realistic noise model, we numerically simulate quantum error correction when the outer code is either a repetition code or a thin rectangular surface code. Our next step toward universal fault-tolerant quantum computation is a protocol for fault-tolerant Toffoli magic state preparation that significantly improves upon the fidelity of physical Toffoli gates at very low qubit cost. To achieve even lower overheads, we devise a new magic-state distillation protocol for Toffoli states. Combining these results together, we obtain realistic full-resource estimates of the physical error rates and overheads needed to run useful fault-tolerant quantum algorithms. We find that with around 1,000 superconducting circuit components, one could construct a fault-tolerant quantum computer that can run circuits which are currently intractable for classical computers. Hardware with 18,000 superconducting circuit components, in turn, could simulate the Hubbard model in a regime beyond the reach of classical computing.