Suppressing quantum errors by scaling a surface code logical qubit
read the original abstract
Practical quantum computing will require error rates that are well below what is achievable with physical qubits. Quantum error correction offers a path to algorithmically-relevant error rates by encoding logical qubits within many physical qubits, where increasing the number of physical qubits enhances protection against physical errors. However, introducing more qubits also increases the number of error sources, so the density of errors must be sufficiently low in order for logical performance to improve with increasing code size. Here, we report the measurement of logical qubit performance scaling across multiple code sizes, and demonstrate that our system of superconducting qubits has sufficient performance to overcome the additional errors from increasing qubit number. We find our distance-5 surface code logical qubit modestly outperforms an ensemble of distance-3 logical qubits on average, both in terms of logical error probability over 25 cycles and logical error per cycle ($2.914\%\pm 0.016\%$ compared to $3.028\%\pm 0.023\%$). To investigate damaging, low-probability error sources, we run a distance-25 repetition code and observe a $1.7\times10^{-6}$ logical error per round floor set by a single high-energy event ($1.6\times10^{-7}$ when excluding this event). We are able to accurately model our experiment, and from this model we can extract error budgets that highlight the biggest challenges for future systems. These results mark the first experimental demonstration where quantum error correction begins to improve performance with increasing qubit number, illuminating the path to reaching the logical error rates required for computation.
This paper has not been read by Pith yet.
Forward citations
Cited by 6 Pith papers
-
Proof of a finite threshold for the union-find decoder
Union-find decoder for surface code achieves finite threshold under circuit-level stochastic errors with quasi-polylog parallel runtime bound.
-
Demonstration of logical qubits and repeated error correction with better-than-physical error rates
Logical error rates in [[7,1,3]] and [[12,2,4]] codes are suppressed 9.8-800 times below physical rates on trapped-ion hardware, with repeated correction cycles approaching the error rate of two physical CNOTs.
-
Measurement-Free Toric-Code Memory in Array Globally Controlled Rydberg Array
Proposes a measurement-free toric-code memory protocol in three-species globally controlled Rydberg arrays, with 4x4 simulations showing extended logical lifetime below pseudo-threshold p* ≈ 0.034.
-
Algebra of Bivariate-Bicycle Surface Codes
BBS code dimension equals the algebraic multiplicity of finite nonzero common roots of the defining bivariate polynomials, enabling a root-based prescription for arbitrary boundary shapes that avoids corner correction...
-
Robust design under uncertainty in quantum error mitigation
Presents unbiased uncertainty quantification for post-processing error mitigation and applies it to optimize hyperparameters in Zero Noise Extrapolation and Clifford Data Regression under finite-shot noise.
-
Mixed-state topological order and the errorfield double formulation of decoherence-induced transitions
Decoherence on abelian topological order is modeled as a temporal defect in double TQFT driving boundary anyon condensation transitions classified by Lagrangian subgroups of the doubled order.
discussion (0)
Sign in with ORCID, Apple, or X to comment. Anyone can read and Pith papers without signing in.