Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Log inSign up
Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Blog
Job Board
Q3AS

© 2026 Aqora Quantum S.A.S.

TermsPrivacyLegal Notice

Quantum 2.0 Conference and Exhibition

Photonic quantum networks reveal the nonlocal nature of Bell-local states

Luis Villegas-Aguilar, Emanuele Polino, Farzad Ghafari, Marco Túlio Quintino, Kiarn T. Laverick, Ian R. Berkman, Sven M. J. Rogge, Lynden K. Shalm, Nora Tischler, Eric G. Cavalcanti, Sergei Slussarenko, Geoff J. Pryde

Published Jan 1, 2024• 0 citations
Publisher

Abstract

Bell nonlocality, a fundamental resource for device-independent technologies like quantum key distribution, is highly susceptible to noise. We experimentally demonstrate that single copies of Bell-local states exhibit nonlocality when integrated into a photonic quantum network.
DOI
10.1364/quantum.2024.qw2b.2

Related papers

Nonlocality activation in a photonic quantum network

Luis Villegas-Aguilar, Emanuele Polino, Farzad Ghafari +9 more

Bell nonlocality refers to correlations between two distant, entangled particles that challenge classical notions of local causality. Beyond its foundational significance, nonlocality is crucial for device-independent technologies like quantum key distribution and randomness generation. Nonlocality quickly deteriorates in the presence of noise, and restoring nonlocal correlations requires additional resources. These often come in the form of many instances of the input state and joint measurements, incurring a significant resource overhead. Here, we experimentally demonstrate that single copies of Bell-local states, incapable of violating any standard Bell inequality, can give rise to nonlocality after being embedded into a quantum network of multiple parties. We subject the initial entangled state to a quantum channel that broadcasts part of the state to two independent receivers and certify the nonlocality in the resulting network by violating a tailored Bell-like inequality. We obtain these results without making any assumptions about the prepared states, the quantum channel, or the validity of quantum theory. Our findings have fundamental implications for nonlocality and enable the practical use of nonlocal correlations in real-world applications, even in scenarios dominated by noise.

arXiv:2309.06501•Nature Communications•Apr 10, 2024•12 citations

Experimental activation of quantum nonlocality via a quantum network

Luis Villegas-Aguilar, Emanuele Polino, Sergei Slussarenko +7 more

Quantum nonlocality arising from entangled particles cannot be explained by any classical notion of local causality. In the standard Bell scenario with a source and two measurement stations, entangled states can lose their ability to exhibit nonlocality due to noisy conditions. Given the fundamental and technological significance of nonlocality and the fact that these noisy entangled states can naturally arise in practical situations, it is of utmost importance to unveil their nonlocality. Here, we demonstrate that nonlocal correlations can be generated from quantum states that cannot show nonlocality in bipartite Bell scenarios. We show how to robustly characterize these states and experimentally activate their nonlocality when embedded in a photonic network, by violating classical constraints in this quantum network. These results have implications in foundations of quantum nonlocality and direct applications to quantum technologies by significantly increasing the robustness of nonlocal correlations to noise.

Quantum Communications and Quantum Imaging•Oct 4, 2024•0 citations

Activation of nonlocality for Bell local states

Luis Villegas-Aguilar

Bell’s nonlocality—correlations between two distant, entangled particles that cannot be explained by physical theories based on local causality—remains one of the most celebrated results of quantum foundations. However, these nonlocal correlations eventually disappear under the presence of noise. In this experimental work, we show that nonlocality, inaccessible for noisy states in the two-party scenario, can be activated in a three-node photonic network structure with a single copy of the state. Our results open up new possibilities for network-based quantum information processing applications, central for the development of a future quantum internet.

Photonics for Quantum (PfQ)•Jul 19, 2023•0 citations

Single-photon nonlocality in quantum networks

Paolo Abiuso, Tamás Kriváchy, Emanuel-Cristian Boghiu +3 more

A single-photon maximally entangled state is obtained when a photon impinges on a balanced beamsplitter.Its nonlocal properties have been intensively debated in the quantum optics and foundations communities.It is however clear that a standard Bell test made only of passive optical elements cannot reveal the nonlocality of this state.We show that the nonlocality of single-photon entangled states can nevertheless be revealed in a quantum network made only of beamsplitters and photodetectors.In our protocol, three single-photon entangled states are distributed in a triangle network, introducing indeterminacy in the photons' paths and creating nonlocal correlations without the need for measurements choices.We discuss a concrete experimental realization and provide numerical evidence of the tolerance of our protocol to standard noise sources.Our results show that single-photon entanglement may constitute a promising solution to generate genuine network-nonlocal correlations useful for Bell-based quantum information protocols.

arXiv:2108.01726•Physical Review Research•Mar 29, 2022•36 citations

Quantum networks reveal single-photon nonlocality

Paolo Abiuso, Tamás Kriváchy, Emanuel-Cristian Boghiu +3 more

The state obtained when a single photon impinges on a balanced beamsplitter is often known as single-photon entangled and its nonlocal properties have been the subject of intense debates in the quantum optics and foundations communities. It is however clear that a standard Bell test made only of passive optical elements cannot reveal the nonlocality of this state. We show that the nonlocality of single-photon entangled states can nevertheless be revealed in a quantum network made only of beamsplitters and photodetectors. In our protocol, three single-photon entangled states are distributed in a triangle network, introducing indeterminacy in the photons' paths and creating nonlocal correlations without the need for measurements choices. We discuss a concrete experimental realisation and provide numerical evidence of the tolerance of our protocol to standard noise sources. Our results show that single-photon entanglement may constitute a promising solution to generate genuine network-nonlocal correlations useful for Bell-based quantum information protocols.

•Aug 3, 2021•1 citation

Experimental quantum randomness enhanced by a quantum network

Emanuele Polino, Luis Villegas-Aguilar, Davide Poderini +10 more

The certification of randomness is essential for both fundamental science and information technologies. Unlike traditional random number generators, randomness obtained from nonlocal correlations is fundamentally guaranteed to be unpredictable. However, it is also highly susceptible to noise. Here, we show that extending the conventional bipartite Bell scenario to hybrid quantum networks -- which incorporate both quantum channels and entanglement sources -- enhances the robustness of certifiable randomness. Our protocol even enables randomness to be certified from Bell-local states, broadening the range of quantum states useful for this task. Through both theoretical analysis and experimental validation in a photonic network, we demonstrate enhanced performance and improved noise resilience.

arXiv:2412.16973•Dec 22, 2024•0 citations
Bell nonlocality refers to correlations between two distant, entangled particles that challenge classical notions of local causality. Beyond its foundational significance, nonlocality is crucial for device-independent technologies like quantum key distribution and randomness generation. Nonlocality quickly deteriorates in the presence of noise, and restoring nonlocal correlations requires additional resources. These often come in the form of many instances of the input state and joint measurements, incurring a significant resource overhead. Here, we experimentally demonstrate that single copies of Bell-local states, incapable of violating any standard Bell inequality, can give rise to nonlocality after being embedded into a quantum network of multiple parties. We subject the initial entangled state to a quantum channel that broadcasts part of the state to two independent receivers and certify the nonlocality in the resulting network by violating a tailored Bell-like inequality. We obtain these results without making any assumptions about the prepared states, the quantum channel, or the validity of quantum theory. Our findings have fundamental implications for nonlocality and enable the practical use of nonlocal correlations in real-world applications, even in scenarios dominated by noise.
Quantum nonlocality arising from entangled particles cannot be explained by any classical notion of local causality. In the standard Bell scenario with a source and two measurement stations, entangled states can lose their ability to exhibit nonlocality due to noisy conditions. Given the fundamental and technological significance of nonlocality and the fact that these noisy entangled states can naturally arise in practical situations, it is of utmost importance to unveil their nonlocality. Here, we demonstrate that nonlocal correlations can be generated from quantum states that cannot show nonlocality in bipartite Bell scenarios. We show how to robustly characterize these states and experimentally activate their nonlocality when embedded in a photonic network, by violating classical constraints in this quantum network. These results have implications in foundations of quantum nonlocality and direct applications to quantum technologies by significantly increasing the robustness of nonlocal correlations to noise.
Bell’s nonlocality—correlations between two distant, entangled particles that cannot be explained by physical theories based on local causality—remains one of the most celebrated results of quantum foundations. However, these nonlocal correlations eventually disappear under the presence of noise. In this experimental work, we show that nonlocality, inaccessible for noisy states in the two-party scenario, can be activated in a three-node photonic network structure with a single copy of the state. Our results open up new possibilities for network-based quantum information processing applications, central for the development of a future quantum internet.
A single-photon maximally entangled state is obtained when a photon impinges on a balanced beamsplitter.Its nonlocal properties have been intensively debated in the quantum optics and foundations communities.It is however clear that a standard Bell test made only of passive optical elements cannot reveal the nonlocality of this state.We show that the nonlocality of single-photon entangled states can nevertheless be revealed in a quantum network made only of beamsplitters and photodetectors.In our protocol, three single-photon entangled states are distributed in a triangle network, introducing indeterminacy in the photons' paths and creating nonlocal correlations without the need for measurements choices.We discuss a concrete experimental realization and provide numerical evidence of the tolerance of our protocol to standard noise sources.Our results show that single-photon entanglement may constitute a promising solution to generate genuine network-nonlocal correlations useful for Bell-based quantum information protocols.
The state obtained when a single photon impinges on a balanced beamsplitter is often known as single-photon entangled and its nonlocal properties have been the subject of intense debates in the quantum optics and foundations communities. It is however clear that a standard Bell test made only of passive optical elements cannot reveal the nonlocality of this state. We show that the nonlocality of single-photon entangled states can nevertheless be revealed in a quantum network made only of beamsplitters and photodetectors. In our protocol, three single-photon entangled states are distributed in a triangle network, introducing indeterminacy in the photons' paths and creating nonlocal correlations without the need for measurements choices. We discuss a concrete experimental realisation and provide numerical evidence of the tolerance of our protocol to standard noise sources. Our results show that single-photon entanglement may constitute a promising solution to generate genuine network-nonlocal correlations useful for Bell-based quantum information protocols.
The certification of randomness is essential for both fundamental science and information technologies. Unlike traditional random number generators, randomness obtained from nonlocal correlations is fundamentally guaranteed to be unpredictable. However, it is also highly susceptible to noise. Here, we show that extending the conventional bipartite Bell scenario to hybrid quantum networks -- which incorporate both quantum channels and entanglement sources -- enhances the robustness of certifiable randomness. Our protocol even enables randomness to be certified from Bell-local states, broadening the range of quantum states useful for this task. Through both theoretical analysis and experimental validation in a photonic network, we demonstrate enhanced performance and improved noise resilience.