Quantum computers just cleared a major hurdle. Japan's RIKEN lab ran 5 silicon qubits simultaneously, and kept fidelity above 99.9%. For context: fault-tolerant quantum computing requires ~99.9% fidelity per operation to correct its own errors. Below that threshold, errors accumulate faster than they can be fixed. The problem: running multiple qubits through a shared microwave line causes phase errors called AC Stark shifts. RIKEN's fix: a calibration protocol using qubit pairs to cancel the shifts, no individual calibration needed for every combination. Single-qubit gates hit 99.999%. Five qubits at once: 99.9%. The key advantage: silicon qubits can be made with existing semiconductor chip factories. No exotic materials. No new fabs. RIKEN Center for Emergent Matter Science. Nature Physics, Oct 15 2026.