Fault-Tolerant Quantum Computing

Capability executing quantum algorithms reliably despite imperfect hardware through quantum error correction encoding logical qubits. Current: 2-3 logical qubits demonstrated, full fault tolerance (millions logical) years away. Essential for CRQC breaking RSA/ECC.

Shor's requires millions sequential gates. Without error correction, errors accumulate destroying computation. Fault tolerance overcomes hardware limitations.

Current: 1-10 fault-tolerant logical qubits, insufficient for Shor's. Industry: 100s-1000s by 2030, millions by 2040. PQC migration references milestones.