Universality of state-independent violation of correlation inequalities for noncontextual theories

Phys Rev Lett. 2009 Jul 31;103(5):050401. doi: 10.1103/PhysRevLett.103.050401. Epub 2009 Jul 28.

Abstract

We show that the state-independent violation of inequalities for noncontextual hidden variable theories introduced in [Phys. Rev. Lett. 101, 210401 (2008)] is universal, i.e., occurs for any quantum mechanical system in which noncontextuality is meaningful. We describe a method to obtain state-independent violations for any system of dimension d> or =3. This universality proves that, according to quantum mechanics, there are no "classical" states.