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QI: Fachverband Quanteninformation
QI 39: Quantum Foundations
QI 39.1: Vortrag
Freitag, 14. März 2025, 11:00–11:15, HS VIII
Discovering Local Hidden-Variable Models for Arbitrary Multipartite Entangled States and Arbitrary Measurements — •Nick von Selzam1 and Florian Marquardt1,2 — 1Max Planck Institute for the Science of Light, Erlangen — 2Friedrich-Alexander-Universität Erlangen-Nürnberg
Measurement correlations in quantum systems can exhibit non-local behaviour, a fundamental aspect of quantum mechanics with applications such as device-independent quantum information processing. However, it is in general not known which states are local and which ones are not. In particular, it remains an outstanding challenge to explicitly construct local hidden-variable (LHV) models for arbitrary multipartite entangled states. To address this, we use gradient-descent algorithms from machine learning to find LHV models which reproduce the statistics of arbitrary measurements for quantum many-body states. In contrast to previous approaches, our method employs a general ansatz, enabling it to discover LHV models for all local states. Therefore, it for example provides actual estimates for the critical noise levels at which two-qubit Werner states and three-qubit GHZ and W states become local. Furthermore, we find evidence suggesting that two-spin subsystems in the ground states of translationally invariant Hamiltonians are genuinely local, while bigger subsystems are in general not. Our method now offers a quantitative tool for determining the regimes of non-locality in any given physical context, such as non-equilibrium, decoherence or disorder.
ArXiv: 2407.04673
Keywords: Bell Non-Locality; Local Hidden-Variable Models; Critical Visibility of Werner States; Machine Learning for Quantum