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

TL;DR

This paper demonstrates that quantum systems universally violate noncontextual inequalities regardless of their state, establishing the absence of classical states in quantum mechanics for systems of dimension greater than two.

Contribution

It introduces a method to achieve state-independent violations of noncontextual inequalities for any quantum system with dimension greater than two, proving their universality.

Findings

Violations occur for all quantum states in systems with dimension > 2

No classical states exist in quantum mechanics according to these violations

The method applies broadly to any such quantum system

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 > 2. This universality proves that, according to quantum mechanics, there are no "classical" states.