Quantum Error Correction Fault-Tolerance Threshold Achieved

Google Quantum AI and IBM independently achieved practical quantum error correction below the fault-tolerance threshold in 2025 — the technical milestone that separates toy quantum computers from machines capable of solving real problems. The specific achievement: maintaining a logical qubit with error rates below the surface code threshold for 1 million operations. Previous demonstrations degraded in hundreds of operations. IBM Eagle R3 processor demonstrated quantum advantage on a classically intractable chemistry simulation (the ground state energy of a vanadium complex relevant to nitrogen fixation and fertilizer production), with results matching the best classical approximations in a fraction of the compute time. The practical timeline to quantum advantage in drug discovery, materials science, and optimization problems: most researchers now cite 2028-2032 rather than the previously cited 2030-2040 range. The cryptography implications are significant — NIST post-quantum cryptography standards finalized in 2024 are becoming urgent.