reported
Reported evidence
Google Quantum AI and collaborators reported below-threshold surface-code memories on the Willow superconducting processor, including distance-5 and distance-7 codes. The manuscript first appeared on August 24, 2024; the Nature publication appeared online in December 2024.
Sources: Google Quantum AI and collaborators, research manuscript
interpretation
Why it matters
Suppressing logical memory errors as code size grows is evidence for a key error-correction requirement. It does not demonstrate a profitable application, unrestricted fault-tolerant computation or independent replication.
Sources: Google Quantum AI and collaborators, research manuscript
interpretation
Comparison boundary
Read the code distances, decoding conditions and error definition in the paper. Do not compare this memory result directly with a vendor's raw physical-qubit total. Commercial usefulness is not established by this example.
Sources: Google Quantum AI and collaborators, research manuscript
reported
Source revision note
Source update reviewed October 10, 2026: the authors corrected Figure 3a’s repetition-code axis and legend labels on April 28, 2026. The notice concerns that repetition-code figure. It does not state that the main surface-code memory result was retracted. This guide does not reproduce numerical benchmark claims.
Sources: Nature
Sources and review scope
Source-linked. Editorial review: .