State-independent quantum contextuality with single photons

TL;DR

This paper demonstrates experimentally that single photons exhibit state-independent quantum contextuality, violating noncontextual inequalities regardless of their quantum state, highlighting fundamental quantum properties relevant to quantum information.

Contribution

The study provides the first experimental demonstration of state-independent contextuality with single photons, showing universal tests that defy noncontextual explanations.

Findings

20 single-photon states violate the inequality by at least 419 standard deviations

Results are independent of the photon’s quantum state

Supports the universality of quantum contextuality in quantum systems

Abstract

We present an experimental state-independent violation of an inequality for noncontextual theories on single particles. We show that 20 different single-photon states violate an inequality which involves correlations between results of sequential compatible measurements by at least 419 standard deviations. Our results show that, for any physical system, even for a single system, and independent of its state, there is a universal set of tests whose results do not admit a noncontextual interpretation. This sheds new light on the role of quantum mechanics in quantum information processing.