In an ironic twist, physicists have shown that the very property that can be used to show that quantum computing devices can solve some problems that classical computers cannot also makes it impossible to efficiently certify that this “quantum supremacy” has indeed been achieved, for a wide variety of schemes. In quantum computing, the issue of certification is crucial for formally verifying the superior computing power of quantum devices.
Source:
https://phys.org/news/2019-06-quantum-supremacy-efficient-certification-difficult.html