Tailoring Bell inequalities to the qudit toric code and self testing

Fuente: arXiv
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Main Authors: Vallée, Eloïc, Makuta, Owidiusz, Emonts, Patrick, Samajdar, Rhine, Tura, Jordi
Format: Preprint
Published: 2025
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author Vallée, Eloïc
Makuta, Owidiusz
Emonts, Patrick
Samajdar, Rhine
Tura, Jordi
author_facet Vallée, Eloïc
Makuta, Owidiusz
Emonts, Patrick
Samajdar, Rhine
Tura, Jordi
contents Bell nonlocality provides a robust scalable route to the efficient certification of quantum states. Here, we introduce a general framework for constructing Bell inequalities tailored to the $\mathbb{Z}_d$ toric code for odd prime local dimensions. Selecting a suitable subset of stabilizer operators and mapping them to generalized measurement observables, we compute multipartite Bell expressions whose quantum maxima admit a sum-of-squares decomposition. We show that these inequalities are maximally violated by all states in the ground-state manifold of the $\mathbb{Z}_d$ toric code, and determine their classical (local) bounds through a combination of combinatorial tiling arguments and explicit optimization. As a concrete application, we analyze the case of $d=3$ and demonstrate that the maximal violation self-tests the full qutrit toric-code subspace, up to local isometries and complex conjugation. This constitutes, to our knowledge, the first-ever example of self-testing a qutrit subspace. Extending these constructions, we further present schemes to enhance the ratio of classical--quantum bounds and thus improve robustness to experimental imperfections. Our results establish a pathway toward device-independent certification of highly entangled topological quantum matter and provide new tools for validating qudit states in error-correcting codes and quantum simulation platforms.
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id arxiv_https___arxiv_org_abs_2512_00146
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Tailoring Bell inequalities to the qudit toric code and self testing
Vallée, Eloïc
Makuta, Owidiusz
Emonts, Patrick
Samajdar, Rhine
Tura, Jordi
Quantum Physics
Bell nonlocality provides a robust scalable route to the efficient certification of quantum states. Here, we introduce a general framework for constructing Bell inequalities tailored to the $\mathbb{Z}_d$ toric code for odd prime local dimensions. Selecting a suitable subset of stabilizer operators and mapping them to generalized measurement observables, we compute multipartite Bell expressions whose quantum maxima admit a sum-of-squares decomposition. We show that these inequalities are maximally violated by all states in the ground-state manifold of the $\mathbb{Z}_d$ toric code, and determine their classical (local) bounds through a combination of combinatorial tiling arguments and explicit optimization. As a concrete application, we analyze the case of $d=3$ and demonstrate that the maximal violation self-tests the full qutrit toric-code subspace, up to local isometries and complex conjugation. This constitutes, to our knowledge, the first-ever example of self-testing a qutrit subspace. Extending these constructions, we further present schemes to enhance the ratio of classical--quantum bounds and thus improve robustness to experimental imperfections. Our results establish a pathway toward device-independent certification of highly entangled topological quantum matter and provide new tools for validating qudit states in error-correcting codes and quantum simulation platforms.
title Tailoring Bell inequalities to the qudit toric code and self testing
topic Quantum Physics
url https://arxiv.org/abs/2512.00146