Quantum Supremacy
The demonstration that a quantum computer performs a task no classical computer can do in feasible time.
Definition
Quantum supremacy (or quantum advantage) is the milestone of a quantum computer completing a specific task that would be practically impossible for any classical computer in reasonable time. The chosen tasks are usually contrived to favor quantum hardware, such as sampling from random circuits.
Each supremacy claim invites a classical counterattack, and several have been partially answered by improved simulation or clever algorithms, narrowing the gap. This back-and-forth is healthy science: it sharpens the benchmarks and clarifies where quantum hardware truly exceeds classical reach.
The milestone is scientific rather than practical: the tasks chosen to demonstrate it are constructed to be hard for classical computers and are usually useless in themselves. Repeated classical counterattacks have narrowed several claimed margins, which is healthy, since it forces honest, well-defined benchmarks. The open question the field is actually chasing is not supremacy on a contrived task but advantage on a valuable one.
Caveats
- Demonstrations often use tasks with no practical use.
- Classical algorithms sometimes catch up, narrowing claimed gaps.
- It does not imply general-purpose quantum usefulness.
Why it matters
Supremacy experiments prove quantum devices can exceed classical simulation in principle, an important scientific marker. They do not yet mean quantum computers solve valuable problems better, a distinction that matters when assessing hype.
Fusion connection
Kronos evaluates quantum claims on whether they solve a useful problem, not on supremacy benchmarks, keeping design work grounded in verified classical methods.