Experimental certification of multipartite Bell correlations using only few-body symmetric correlations
Abstract
Certifying Bell correlations in increasingly larger multipartite quantum systems is challenging because conventional Bell inequalities rely on many-body correlations, which become experimentally demanding to estimate as system size grows. Here we demonstrate that multipartite Bell correlations can be certified using few-body permutation-invariant (PI) correlations with a fixed maximal correlation order. We experimentally test few-body PI Bell correlation witnesses tailored for six- and eight-photon postselected Dicke states. The addition of a few four-body correlators is found to significantly enhance the noise tolerance compared with previously studied two-body witnesses: for instance, for six qubits, the selected witness tolerates a white-noise fraction of pc≈0.301, compared with pc≈0.048 for the best two-body PI inequality with the same two settings per party. For six and eight photons respectively, we observe violations of the witness bounds by $32$ and $8.9$ standard deviations, arising from postselected polarisation states with fidelities of 0.933(4) and $0.916(11)$ to the corresponding half-excitation Dicke states. The witnesses for the six- and eight-photon cases use the same symmetric two- and four-body correlators, just with different coefficients. These results demonstrate an experimentally accessible approach for certifying multipartite Bell correlations in larger systems without requiring full-body correlation measurements.
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BibTeX
@misc{sun2026experimental,
title = {{Experimental certification of multipartite Bell correlations using only few-body symmetric correlations}},
author = {Jiacheng Sun and Mengyao Hu and Paweł Cieśliński and Jinfu Chen and Fei Shi and Bowen Wang and Hongyu Yang and Jizhou Wu and Jordi Tura and Valerio Scarani and Dian Wu and Jian Wu},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2609.37442},
eprint = {2609.37442},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2609.37442},
}
RIS
TY - UNPB
TI - Experimental certification of multipartite Bell correlations using only few-body symmetric correlations
AU - Jiacheng Sun
AU - Mengyao Hu
AU - Paweł Cieśliński
AU - Jinfu Chen
AU - Fei Shi
AU - Bowen Wang
AU - Hongyu Yang
AU - Jizhou Wu
AU - Jordi Tura
AU - Valerio Scarani
AU - Dian Wu
AU - Jian Wu
PY - 2026
DA - 2026/09/29
PB - arXiv
DO - 10.48550/arxiv.2609.37442
UR - https://arxiv.org/abs/2609.37442
AB - Certifying Bell correlations in increasingly larger multipartite quantum systems is challenging because conventional Bell inequalities rely on many-body correlations, which become experimentally demanding to estimate as system size grows. Here we demonstrate that multipartite Bell correlations can be certified using few-body permutation-invariant (PI) correlations with a fixed maximal correlation order. We experimentally test few-body PI Bell correlation witnesses tailored for six- and eight-photon postselected Dicke states. The addition of a few four-body correlators is found to significantly enhance the noise tolerance compared with previously studied two-body witnesses: for instance, for six qubits, the selected witness tolerates a white-noise fraction of p_c≈0.301, compared with p_c≈0.048 for the best two-body PI inequality with the same two settings per party. For six and eight photons respectively, we observe violations of the witness bounds by $32$ and $8.9$ standard deviations, arising from postselected polarisation states with fidelities of 0.933(4) and $0.916(11)$ to the corresponding half-excitation Dicke states. The witnesses for the six- and eight-photon cases use the same symmetric two- and four-body correlators, just with different coefficients. These results demonstrate an experimentally accessible approach for certifying multipartite Bell correlations in larger systems without requiring full-body correlation measurements.
ER -