Story perspectives

Bayesian Phase Estimation Reaches Fault-Tolerant Break-Even

6/21/2026

Summary

Story summary

Researchers demonstrated Bayesian quantum phase estimation with quantum error detection, publishing the results in Phys. Rev. Res. 6, 013221 (2024).
A team entangled four logical qubits beyond the break-even point using a nonlocal code, reported in Phys. Rev. Lett. 133, 180601 (2024).
Scientists scaled logic in the colour code on a superconducting processor and realized fault-tolerant entangling gates, described in Nature 645, 614–619 (2025) and a 2022 arXiv preprint (arXiv:2208.01863).

History

Historical Context

In 2001 IBM used a seven-qubit liquid-state NMR processor to run Shor’s algorithm, marking the first experimental factoring demonstration. Since then, error-correction breakthroughs—such as the 2016 logical-qubit break-even and the 2023 Google surface-code error reduction—have enabled Google AI Quantum and MIT’s Center for Quantum Engineering to scale colour-code logical qubits. These steps move fault-tolerant processors toward commercial use, prompting U.S. defense funding.

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Story summary

Researchers demonstrated Bayesian quantum phase estimation with quantum error detection, publishing the results in Phys. Rev. Res. 6, 013221 (2024).
A team entangled four logical qubits beyond the break-even point using a nonlocal code, reported in Phys. Rev. Lett. 133, 180601 (2024).
Scientists scaled logic in the colour code on a superconducting processor and realized fault-tolerant entangling gates, described in Nature 645, 614–619 (2025) and a 2022 arXiv preprint (arXiv:2208.01863).

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