All-versus-nothing nonlocality for multiple observers in quantum networks
Phys. Rev. A 113, 022435 – Published 20 February, 2026
DOI: https://doi.org/10.1103/jtpq-98v4
Abstract
Nonlocality serves as a fundamental quantum resource with essential applications in information processing tasks. All-versus-nothing (AVN) tests provide the strongest demonstration of quantum-classical conflicts without statistical loopholes. We demonstrate AVN nonlocality in cyclic quantum networks with multiple observers, revealing an elegant logical structure that enables violations with certainty. These AVN paradoxes are reformulated as Hardy-type arguments achieving unit probability, providing a powerful framework for network nonlocality certification. Remarkably, by assuming global noncontextual deterministic value assignments, the proof of our approach can be reformulated as a Kochen-Specker type contradiction in a state-independent fashion, establishing fundamental constraints on hidden-variable theories. These results provide a scalable certification method for multipartite nonlocality in quantum networks and enable novel quantum information protocols in network architectures beyond bipartite systems, paving the way for distributed quantum computing and communication applications.
