Practically state-independent test of contextuality with 9 observables

TL;DR

This paper introduces a practical, state-independent test of quantum contextuality using nine measurements on a three-level system, which is violated by all states except the maximally mixed one, highlighting a new approach to testing quantum foundations.

Contribution

It presents a novel inequality-based test of quantum contextuality that is practically implementable and distinguishes itself from previous state-independent tests.

Findings

The test is violated by all pure and mixed states except the maximally mixed state.

It provides a practical method for experimentally verifying quantum contextuality.

The inequality offers a new perspective on the differences between state-dependent and state-independent tests.

Abstract

We propose a test of quantum contextuality for a single three-level system that uses nine projective measurements. It has a form of an inequality that has to be satisfied by any non-contextual theory and which is violated by any quantum state, except for the maximally mixed one. Due to the fact that there is only a single state that does not exhibit contextuality, it is natural to ask what the difference between state-independent tests and the one proposed here is.