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

arXiv:2105.09380 · Physical Review A

Any physical theory of nature must be boundlessly multipartite nonlocal

Xavier Coiteux-Roy, Elie Wolfe, Marc-Olivier Renou

Published Nov 10, 2021• 26 citations
arXivHTMLPDF

Abstract

We introduce the class of genuinely local operations and shared randomness multipartite nonlocal correlations, that is, correlations between $N$ parties that cannot be obtained from unlimited shared randomness supplemented by any composition of $(N\ensuremath{-}1)$-shared causal generalized probabilistic theory (GPT) resources. We then show that noisy $N$-partite Greenberger-Horne-Zeilinger (GHZ) quantum states as well as the three-partite $W$ quantum state can produce such correlations. This proves, if the operational predictions of quantum theory are correct, that nature's nonlocality must be boundlessly multipartite in any causal GPT. We develop a computational method which certifies that a noisy $N=3$ GHZ quantum state with fidelity $85%$ satisfies this property, making an experimental demonstration of our results within reach. We provide our definition and contrast it with preexisting notions of genuine multipartite nonlocality. This work extends a more compact parallel Letter [X. Coiteux-Roy et al., No Bipartite-Nonlocal Causal Theory Can Explain Nature's Correlations, Phys. Rev. Lett. 127, 200401 (2021)] on the same subject and provides all the required technical proofs.

DOI
10.1103/physreva.104.052207

Related papers

No Bipartite-Nonlocal Causal Theory Can Explain Nature’s Correlations

Xavier Coiteux-Roy, Elie Wolfe, Marc-Olivier Renou

We show that some tripartite quantum correlations are inexplicable by any causal theory involving bipartite nonclassical common causes and unlimited shared randomness. This constitutes a device-independent proof that nature's nonlocality is fundamentally at least tripartite in every conceivable physical theory---no matter how exotic. To formalize this claim, we are compelled to substitute Svetlichny's historical definition of genuine tripartite nonlocality with a novel theory-agnostic definition tied to the framework of local operations and shared randomness. A companion article by Coiteux-Roy et al. generalizes these concepts to any $N\ensuremath{\ge}3$ number of parties, providing experimentally amenable device-independent inequality constraints along with quantum correlations violating them, thereby certifying that nature's nonlocality must be boundlessly multipartite.

arXiv:2105.09381•Physical Review Letters•Nov 10, 2021•0 citations

No Bipartite-Nonlocal Causal Theory Can Explain Nature's Correlations.

Xavier Coiteux-Roy, Elie Wolfe, Marc-Olivier Renou

We show that some tripartite quantum correlations are inexplicable by any causal theory involving bipartite nonclassical common causes and unlimited shared randomness. This constitutes a device-independent proof that nature's nonlocality is fundamentally at least tripartite in every conceivable physical theory-no matter how exotic. To formalize this claim, we are compelled to substitute Svetlichny's historical definition of genuine tripartite nonlocality with a novel theory-agnostic definition tied to the framework of local operations and shared randomness. A companion article by Coiteux-Roy et al. generalizes these concepts to any N≥3 number of parties, providing experimentally amenable device-independent inequality constraints along with quantum correlations violating them, thereby certifying that nature's nonlocality must be boundlessly multipartite.

•Nov 12, 2021•47 citations

Test of Genuine Multipartite Nonlocality

Ya-Li Mao, Zheng-Da Li, Sixia Yu +1 more

While Bell nonlocality of a bipartite system is counterintuitive, multipartite nonlocality in our many-body world turns out to be even more so. Recent theoretical study reveals in a theory-agnostic manner that genuine multipartite nonlocal correlations cannot be explained by any causal theory involving fewer-partite nonclassical resources and global shared randomness. Here, we provide a Bell-type inequality as a test for genuine multipartite nonlocality in network by exploiting a matrix representation of the causal structure of a multipartite system. We further present experimental demonstrations that both four-photon GHZ state and generalized four-photon GHZ state significantly violate the inequality, i.e., the observed four-partite correlations resist explanations involving three-way nonlocal resources subject to local operations and common shared randomness, hence confirming that nature is boundless multipartite nonlocal.

arXiv:2201.12753•Physical Review Letters•Oct 4, 2022•27 citations

Experimental Demonstration that No Tripartite-Nonlocal Causal Theory Explains Nature’s Correlations

Huan Cao, Marc-Olivier Renou, Chao Zhang +7 more

Quantum theory predicts the existence of genuinely tripartite-entangled states, which cannot be obtained from local operations over any bipartite-entangled states and unlimited shared randomness. Some of us recently proved that this feature is a fundamental signature of quantum theory. The state |GHZ_{3}⟩=(|000⟩+|111⟩)/sqrt[2] gives rise to tripartite quantum correlations that cannot be explained by any causal theory limited to bipartite nonclassical common causes of any kind (generalizing entanglement) assisted with unlimited shared randomness. Hence, any conceivable physical theory that would reproduce quantum predictions will necessarily include genuinely tripartite resources. In this Letter, we verify that such tripartite correlations are experimentally achievable. We derive a new device-independent witness capable of falsifying causal theories wherein nonclassical resources are merely bipartite. Using a high-performance photonic |GHZ_{3}⟩ state with fidelities of 0.9741±0.002, we provide a clear experimental violation of that witness by more than 26.3 standard deviations, under the locality and fair sampling assumption. We generalize our Letter to the |GHZ_{4}⟩ state, obtaining correlations that cannot be explained by any causal theory limited to tripartite nonclassical common causes assisted with unlimited shared randomness.

arXiv:2201.12754•Physical Review Letters•Oct 4, 2022•21 citations

Experimental Demonstration of Genuine Tripartite Nonlocality under Strict Locality Conditions

Liang Huang, Xuemei Gu, Yang-Fan Jiang +9 more

Nonlocality captures one of the counterintuitive features of nature that defies classical intuition. Recent investigations reveal that our physical world's nonlocality is at least tripartite; i.e., genuinely tripartite nonlocal correlations in nature cannot be reproduced by any causal theory involving bipartite nonclassical resources and unlimited shared randomness. Here, by allowing the fair sampling assumption and postselection, we experimentally demonstrate such genuine tripartite nonlocality in a network under strict locality constraints that are ensured by spacelike separating all relevant events and employing fast quantum random number generators and high-speed polarization measurements. In particular, for a photonic quantum triangular network we observe a locality-loophole-free violation of the Bell-type inequality by 7.57 standard deviations for a postselected tripartite Greenberger-Horne-Zeilinger state of fidelity (93.13±0.24)%, which convincingly disproves the possibility of simulating genuine tripartite nonlocality by bipartite nonlocal resources with globally shared randomness.

arXiv:2203.00889•Physical Review Letters•Aug 2, 2022•15 citations

Noise robust self testing from genuine local operation shared randomness multipartite nonlocality Tests

Som Kanjilal

Violation of the $N$-partite inequality introduced in Phys. Rev. Lett. 129, 150401 (2022) for genuine multipartite nonlocality under local operations and shared randomness (LOSR) rules out all causal-network models obtained by locally composing arbitrary resources involving at most $N-1$ parties, even when supplemented by shared randomness among all $N$ parties. Here, we demonstrate a device-independent self-test protocol for this. We further establish an analytic noise-robust self-test. For a Bell-score deficit $ε$, we derive explicit $O(\sqrtε)$ vector-norm bounds for the state and the corresponding measurement actions.

quant-pharXiv:2609.15436•Sep 15, 2026•0 citations
We introduce the class of genuinely local operations and shared randomness multipartite nonlocal correlations, that is, correlations between NNN parties that cannot be obtained from unlimited shared randomness supplemented by any composition of (N\ensuremath−1)(N\ensuremath{-}1)(N\ensuremath−1)-shared causal generalized probabilistic theory (GPT) resources. We then show that noisy NNN-partite Greenberger-Horne-Zeilinger (GHZ) quantum states as well as the three-partite WWW quantum state can produce such correlations. This proves, if the operational predictions of quantum theory are correct, that nature's nonlocality must be boundlessly multipartite in any causal GPT. We develop a computational method which certifies that a noisy N=3N=3N=3 GHZ quantum state with fidelity 8585%85 satisfies this property, making an experimental demonstration of our results within reach. We provide our definition and contrast it with preexisting notions of genuine multipartite nonlocality. This work extends a more compact parallel Letter [X. Coiteux-Roy et al., No Bipartite-Nonlocal Causal Theory Can Explain Nature's Correlations, Phys. Rev. Lett. 127, 200401 (2021)] on the same subject and provides all the required technical proofs.
We show that some tripartite quantum correlations are inexplicable by any causal theory involving bipartite nonclassical common causes and unlimited shared randomness. This constitutes a device-independent proof that nature's nonlocality is fundamentally at least tripartite in every conceivable physical theory---no matter how exotic. To formalize this claim, we are compelled to substitute Svetlichny's historical definition of genuine tripartite nonlocality with a novel theory-agnostic definition tied to the framework of local operations and shared randomness. A companion article by Coiteux-Roy et al. generalizes these concepts to any $N\ensuremath{\ge}3$ number of parties, providing experimentally amenable device-independent inequality constraints along with quantum correlations violating them, thereby certifying that nature's nonlocality must be boundlessly multipartite.
We show that some tripartite quantum correlations are inexplicable by any causal theory involving bipartite nonclassical common causes and unlimited shared randomness. This constitutes a device-independent proof that nature's nonlocality is fundamentally at least tripartite in every conceivable physical theory-no matter how exotic. To formalize this claim, we are compelled to substitute Svetlichny's historical definition of genuine tripartite nonlocality with a novel theory-agnostic definition tied to the framework of local operations and shared randomness. A companion article by Coiteux-Roy et al. generalizes these concepts to any N≥3 number of parties, providing experimentally amenable device-independent inequality constraints along with quantum correlations violating them, thereby certifying that nature's nonlocality must be boundlessly multipartite.
While Bell nonlocality of a bipartite system is counterintuitive, multipartite nonlocality in our many-body world turns out to be even more so. Recent theoretical study reveals in a theory-agnostic manner that genuine multipartite nonlocal correlations cannot be explained by any causal theory involving fewer-partite nonclassical resources and global shared randomness. Here, we provide a Bell-type inequality as a test for genuine multipartite nonlocality in network by exploiting a matrix representation of the causal structure of a multipartite system. We further present experimental demonstrations that both four-photon GHZ state and generalized four-photon GHZ state significantly violate the inequality, i.e., the observed four-partite correlations resist explanations involving three-way nonlocal resources subject to local operations and common shared randomness, hence confirming that nature is boundless multipartite nonlocal.
Quantum theory predicts the existence of genuinely tripartite-entangled states, which cannot be obtained from local operations over any bipartite-entangled states and unlimited shared randomness. Some of us recently proved that this feature is a fundamental signature of quantum theory. The state |GHZ_{3}⟩=(|000⟩+|111⟩)/sqrt[2] gives rise to tripartite quantum correlations that cannot be explained by any causal theory limited to bipartite nonclassical common causes of any kind (generalizing entanglement) assisted with unlimited shared randomness. Hence, any conceivable physical theory that would reproduce quantum predictions will necessarily include genuinely tripartite resources. In this Letter, we verify that such tripartite correlations are experimentally achievable. We derive a new device-independent witness capable of falsifying causal theories wherein nonclassical resources are merely bipartite. Using a high-performance photonic |GHZ_{3}⟩ state with fidelities of 0.9741±0.002, we provide a clear experimental violation of that witness by more than 26.3 standard deviations, under the locality and fair sampling assumption. We generalize our Letter to the |GHZ_{4}⟩ state, obtaining correlations that cannot be explained by any causal theory limited to tripartite nonclassical common causes assisted with unlimited shared randomness.
Nonlocality captures one of the counterintuitive features of nature that defies classical intuition. Recent investigations reveal that our physical world's nonlocality is at least tripartite; i.e., genuinely tripartite nonlocal correlations in nature cannot be reproduced by any causal theory involving bipartite nonclassical resources and unlimited shared randomness. Here, by allowing the fair sampling assumption and postselection, we experimentally demonstrate such genuine tripartite nonlocality in a network under strict locality constraints that are ensured by spacelike separating all relevant events and employing fast quantum random number generators and high-speed polarization measurements. In particular, for a photonic quantum triangular network we observe a locality-loophole-free violation of the Bell-type inequality by 7.57 standard deviations for a postselected tripartite Greenberger-Horne-Zeilinger state of fidelity (93.13±0.24)%, which convincingly disproves the possibility of simulating genuine tripartite nonlocality by bipartite nonlocal resources with globally shared randomness.
Violation of the NNN-partite inequality introduced in Phys. Rev. Lett. 129, 150401 (2022) for genuine multipartite nonlocality under local operations and shared randomness (LOSR) rules out all causal-network models obtained by locally composing arbitrary resources involving at most N−1N-1N−1 parties, even when supplemented by shared randomness among all NNN parties. Here, we demonstrate a device-independent self-test protocol for this. We further establish an analytic noise-robust self-test. For a Bell-score deficit εεε, we derive explicit O(ε)O(\sqrtε)O(ε​) vector-norm bounds for the state and the corresponding measurement actions.