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arXiv · 2604.25901

Testing a continuous-variable noncontextuality inequality with a hybrid-encoded system

Yu Meng·Ying Wang·Clara Henke·Nikolai Bart·Arne Ludwig·Peter Lodahl·Jonas S. Neergaard-Nielsen·Ulrik L. Andersen·Leonardo Midolo·Zheng-Hao Liu
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Abstract

Continuous-variable quantum systems are promising candidates for quantum computing and quantum information processing. It is widely known that quadrature measurements on Gaussian continuous-variable systems admit a noncontextual hidden-variable description. Here, we demonstrate that this description fails once the same Gaussian correlations are instead probed using Hadamard tests. We realize the test with a hybrid discrete--continuous-variable system---the polarization and spatial modes of a single photon deterministically generated from an InAs/GaAs quantum emitter, with the controlled operations being the phase-space displacements selected through the Gottesman--Kitaev--Preskill correspondence. By directly measuring the correlations of the operators, we observe a violation of the noncontextual hidden-variable inequality by 380 standard deviations and independently bound the residual noncommutativity of the implemented operations. Our results open up new possibilities for studying fundamental quantum physics using photonic-encoded continuous-variable systems.

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Yu Meng, Ying Wang, Clara Henke, Nikolai Bart, Arne Ludwig, Peter Lodahl, Jonas S. Neergaard-Nielsen, Ulrik L. Andersen, Leonardo Midolo, Zheng-Hao Liu. 2026-04-28. Testing a continuous-variable noncontextuality inequality with a hybrid-encoded system. https://arxiv.org/abs/2604.25901

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