Quantum Advantage

Quantum advantage (sometimes called quantum supremacy for extreme cases) refers to a scenario where a quantum computer performs a task faster, more accurately, or more efficiently than the best known classical algorithm. There are two levels: (1) Quantum supremacy — demonstrating any task that classical hardware cannot feasibly simulate (Google's 2019 Sycamore result). (2) Practical quantum advantage — outperforming classical methods on a commercially useful problem. As of 2026, quantum supremacy has been demonstrated, but practical quantum advantage for industrially relevant problems has not been confirmed. Claims of quantum advantage should specify the exact task, classical comparison, and whether the advantage holds for problem sizes that matter. Most NISQ-era results show quantum computers performing similarly to (but not better than) classical heuristics for relevant problem sizes.