npj Quantum Information

State-independent test of quantum contextuality with either single photons or coherent light

Dengke Qu, Kunkun Wang, Lei Xiao, Xiang Zhan, Peng Xue

Published Oct 22, 2021• 13 citations

Abstract

Abstract Contextuality is a phenomenon at the heart of quantum mechanics different from classical behavior and has been recently identified as a resource in quantum information processing. Experimental demonstration of contextuality is thus an important goal. We experimentally demonstrate a test of state-independent contextuality in a four-dimensional Hilbert space with single photons and violate the inequality by at least 387 standard deviations. Despite imperfections and possible measurement disturbance, our results cannot be explained in non-contextual models. We also provide a theoretical analysis of a test of contextuality with a coherent light field and show how the definitions affect the emergence of non-classical correlations. Our result sheds new light on the conflict between quantum and classical physics.

DOI: 10.1038/s41534-021-00492-1

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