Proof of the usefulness of a quantum computer. Quantum supremacy means that a quantum computer is capable of solving a problem that a classical computer would take forever to resolve. For example, in 2019, Google claimed its Sycamore quantum computer solved a mathematical problem in three minutes that would take a supercomputer 10,000 years.
Not So Fast
This quantum supremacy claim has been refuted by IBM and others, stating that it would only take a few weeks of classical computation. In addition, the problem that was solved was considered irrelevant for all practical purposes. See quantum computing