Exponential suppression of bit or phase errors with cyclic error correction

By Zijun Chen, K. Satzinger, J. Atalaya, A. Korotkov, A. Dunsworth, D. Sank, C. Quintana, M. McEwen, R. Barends, P. Klimov and 86 more. Nature, 2021

443 citations recorded by the source corpus.

Realizing the potential of quantum computing requires sufficiently low logical error rates1. Many applications call for error rates as low as 10−15 (refs. 2–9), but state-of-the-art quantum platforms typically have physical error rates near 10−3 (refs. 10–14). Quantum error correction15–17 promises to bridge this divide by distributing quantum logical information across many physical qubits in such a way that errors can be detected and corrected. Errors on the encoded logical qubit state can be exponentially suppressed as the number of physical qubits grows, provided that the physical error rates are below a certain threshold and stable over the course of a computation. Here we implement one-dimensional repetition codes embedded in a two-dimensional grid of superconducting qubits that demonstrate exponential suppression of bit-flip or phase-flip errors, reducing logical error per round more than 100-fold when increasing the number of qubits from 5 to 21. Crucially, this error suppression is stable over 50 rounds of error correction. We also introduce a method for analysing error correlations with high precision, allowing us to characterize error locality while performing quantum error correction. Finally, we perform error detection with a small logical qubit using the 2D surface code on the same device18,19 and show that the results from both one- and two-dimensional codes agree with numerical simulations that use a simple depolarizing error model. These experimental demonstrations provide a foundation for building a scalable fault-tolerant quantum computer with superconducting qubits. Repetition codes running many cycles of quantum error correction achieve exponential suppression of errors with increasing numbers of qubits.

Subfields: Artificial Intelligence, Electrical and Electronic Engineering

View Paper: https://www.semanticscholar.org/paper/cad3c8bf766a7588ff3ff299ba1d065c8f901435

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Citations in the corpus

A Race-Track Trapped-Ion Quantum Processor (2023, background): “[97, 98], which use a fixed architecture and parallel syndrome measurements, making for a direct comparison of different distances.”
Engineered dissipation for quantum information science (2022, methodology): “For example, detection of either bit ﬂip or phase ﬂip errors with repetition codes has demonstrated the suppression of logical error rates and favorable scaling on 21 qubits with 50 rounds of quantum error detection 24 .”
Suppressing quantum errors by scaling a surface code logical qubit (2022, unknown): “We attribute this rise to data qubits leaking into non-computational excited states and anticipate that the inclusion of leakage-removal techniques on data qubits would help to mitigate this rise [42, 47–49].”
Realizing repeated quantum error correction in a distance-three surface code (2021, background): “0(9)% i i c phys =1 4 w with respect to states that are, in principle, correctable; see Supplementary Information (section IX).”
Quantum error correction below the surface code threshold (2024, unknown): “This result constitutes a four orders-of-magnitude improvement compared to the lowest logical error per cycle achieved in previous experiments [33].”
A quantum processor based on coherent transport of entangled atom arrays (2021, unknown): “7%, beyond the surface code threshold [37, 66].”
Demonstration of fault-tolerant universal quantum gate operations (2021, background): “State preparation of a topological surface code state [14], repetitive stabilizer measurements in an error-detecting surface code [15, 16] and exponential error suppression in a repetition code [17] have been demonstrated in superconducting architectures.”