2017/02/18 by Ying Li, Simon C. Benjamin · 1 citation
Physics and Astronomy · #quant-ph
paper · pdf · doi:10.1038/s41534-018-0074-2
published as npj Quantum Information 4, 25 (2018) · 15 pages, 12 figures
arxiv created 2017/02/18 · arxiv updated 2018/06/12
In principle a 1D array of nearest-neighbour linked qubits is compatible with fault tolerant quantum computing. However such a restricted topology necessitates a large overhead for shuffling qubits and consequently the fault tolerance threshold is far lower than in 2D architectures. Here we identify a middle ground: a 1D segmented chain which is a linear array of segments, each of which is a well-connected zone with all-to-all connectivity. The architecture is relevant to both ion trap and solid-state systems. We establish that fault tolerance can be achieved either by a surface code alone, or via an additional concatenated four-qubit gauge code. We find that the fault tolerance threshold is 0.12% for 15-qubit segments, while larger segments are superior. For 35 or more qubits per segment one can achieve computation on a meaningful scale with today's state-of-the-art fidelities without the use of the upper concatenation layer, thus minimising the overall device size.