How has quantum computing error correction progressed?

The answer

Quantum error correction (QEC) made landmark progress in 2023-2024. Google's quantum AI team demonstrated that their surface code error correction on 72 superconducting qubits performed better than on 17 qubits - proving for the first time that adding more qubits actually reduces errors, crossing a crucial threshold. Harvard and QuEra used 48 logical qubits with neutral atom arrays to run complex algorithms with error correction in December 2023. IBM's Heron processor, released in late 2023, reduced error rates sufficiently to demonstrate quantum advantage without full error correction using error mitigation techniques. Microsoft and Quantinuum announced in 2024 the creation of four highly reliable logical qubits with 800 times fewer errors than physical qubits, using a combination of topological and standard approaches.