Skip to main content

Thank you for visiting You are using a browser version with limited support for CSS. To obtain the best experience, we recommend you use a more up to date browser (or turn off compatibility mode in Internet Explorer). In the meantime, to ensure continued support, we are displaying the site without styles and JavaScript.


Test your theory

Phys. Rev. Lett. (in the press); preprint at

Quantum theory has been put to many tests and it has passed them all, but it is not the only possible theory to explain the physical world. Unlike classical theories, quantum mechanics does not rest on clear physical principles, and it is therefore difficult to identify it as the one correct theory. Mirjam Weilenmann and Roger Colbeck have now suggested an alternative approach to single out quantum mechanics: they proposed to extend the concept of self-testing quantum states to the theory itself.

When two particles are entangled, separate measurements of each particle are correlated in a way that cannot be reproduced classically. Observing these correlations provides a ‘self-test’ that shows entanglement is present without the need to know any details of the measurement.

Weilenmann and Colbeck proposed searching for self-tests that are satisfied by quantum mechanics but exclude alternative theories. Defining quantum theory via self-tests could provide a more intuitive basis for quantum mechanics, and self-tests could be used to experimentally confirm the validity of quantum theory.

Author information



Corresponding author

Correspondence to Richard Brierley.

Rights and permissions

Reprints and Permissions

About this article

Verify currency and authenticity via CrossMark

Cite this article

Brierley, R. Test your theory. Nat. Phys. 16, 819 (2020).

Download citation


Quick links

Nature Briefing

Sign up for the Nature Briefing newsletter — what matters in science, free to your inbox daily.

Get the most important science stories of the day, free in your inbox. Sign up for Nature Briefing