Quantum Computing

What's actually true

Quantum computers today cannot solve any practical problem faster than classical computers. Google's 2019 "quantum supremacy" experiment solved a contrived problem with no known applications (random circuit sampling) — and was surpassed by classical algorithms within years. Useful quantum error-correction requires thousands of physical qubits per logical qubit, and current devices have 100-1000 noisy physical qubits with error rates too high for fault-tolerant computation. The "NISQ era" (Noisy Intermediate-Scale Quantum) has produced no commercially useful application despite a decade of research. Quantum advantage for practical problems — Shor's algorithm to break RSA, for example — would require millions of physical qubits with error rates orders of magnitude lower than today's hardware. The quantum winter analogy is increasingly invoked by researchers who note that the gap between the "any day now" narrative and the reality of hardware constraints mirrors the AI field in the 1980s. Quantum computing is real science, and progress is being made — but useful, fault-tolerant quantum computers that outperform classical computers on practical problems remain years to decades away.