aiqbench analysis
This experimental study on superconducting hardware reveals a discrepancy between simulated and observed logical fidelity in repetition codes, suggesting that unmodeled qubit frequency drifts effectively convert coherent errors into stochastic ones. The findings highlight a critical nuance in quantum error correction: theoretical predictions for noise impact may not hold in practice without accounting for hardware-induced phase coherence. For researchers, this underscores the necessity of characterizing and mitigating frequency drifts to accurately benchmark logical qubit performance.
Coherent versus stochastic error injection on a repetition-code logical qubit in superconducting hardware
arXiv:2606.07377v1 Announce Type: new Abstract: The performance of quantum error correction (QEC) codes is limited by the underlying physical noise. Theoretical studies show that coherent and stochastic noise have different effects when performing QEC with either surface or repetition codes. We use the bitflip repetition code, realized in a transmon quantum processor, as a testbed to experimentally study the impact of injecting coherent versus stochastic errors on the logical performance. We adapt a scalable free-fermion simulator to simulate the experiments and we modify a subset sampling technique to efficiently sample stochastic noise in the quantum circuit. In the experiment, we do not observe the difference in logical fidelity predicted by simulation for either the distance-3 or distance-5 repetition codes. We hypothesize that this discrepancy could be explained by small drifts in qubit frequencies, which introduce phase-coherent noise that `stochastifies' the injected coherent errors. Our work contributes to advancing an understanding of how coherent errors affect experimental QEC.
Abstract:The performance of quantum error correction (QEC) codes is limited by the underlying physical noise. Theoretical studies show that coherent and stochastic noise have different effects when performing QEC with either surface or repetition codes. We use the bitflip repetition code, realized in a transmon quantum processor, as a testbed to experimentally study the impact of injecting coherent versus stochastic errors on the logical performance. We adapt a scalable free-fermion simulator to simulate the experiments and we modify a subset sampling technique to efficiently sample stochastic noise in the quantum circuit. In the experiment, we do not observe the difference in logical fidelity predicted by simulation for either the distance-3 or distance-5 repetition codes. We hypothesize that this discrepancy could be explained by small drifts in qubit frequencies, which introduce phase-coherent noise that `stochastifies' the injected coherent errors. Our work contributes to advancing an understanding of how coherent errors affect experimental QEC.
arXiv:2606.07377 [quant-ph]
(or arXiv:2606.07377v1 [quant-ph] for this version)
https://doi.org/10.48550/arXiv.2606.07377 Focus to learn more arXiv-issued DOI via DataCite (pending registration)
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