Non-Gaussian Entanglement Hierarchy Based on the Schmidt Number

Fuente: arXiv
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Autori principali: Guo, Jiajie, Liu, Shuheng, Fadel, Matteo, He, Qiongyi
Natura: Preprint
Pubblicazione: 2026
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author Guo, Jiajie
Liu, Shuheng
Fadel, Matteo
He, Qiongyi
author_facet Guo, Jiajie
Liu, Shuheng
Fadel, Matteo
He, Qiongyi
contents Non-Gaussian entanglement is a promising resource in various quantum tasks. A recently defined class identifies entanglement that cannot be generated by applying Gaussian operations to separable inputs. To further explore the entanglement in this context, we introduce a quantitative witness $E_{\rm NG}$ in bipartite bosonic systems, which satisfies $E_{\rm NG}=1$ for all Gaussian-entanglable states, while $E_{\rm NG}>1$ certifies non-Gaussian entanglement. Its ceiling $d=\lceil E_{\rm NG}\rceil$ provides a lower bound on the Schmidt number irreducible by Gaussian transformations, thereby defining a natural hierarchy of non-Gaussian entanglement. For pure states, the condition is sharp and the hierarchy reflects the complexity of state learning. We benchmark the framework with some paradigmatic non-Gaussian states, such as NOON states and squeezed Kerr states, and analyze its robustness against loss. Moreover, we construct an experimentally economical NOON-type witness requiring only four density-matrix element measurements. These results establish an operationally meaningful and experimentally accessible framework for identifying non-Gaussian entanglement resources in continuous-variable quantum platforms.
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id arxiv_https___arxiv_org_abs_2605_18605
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Non-Gaussian Entanglement Hierarchy Based on the Schmidt Number
Guo, Jiajie
Liu, Shuheng
Fadel, Matteo
He, Qiongyi
Quantum Physics
Non-Gaussian entanglement is a promising resource in various quantum tasks. A recently defined class identifies entanglement that cannot be generated by applying Gaussian operations to separable inputs. To further explore the entanglement in this context, we introduce a quantitative witness $E_{\rm NG}$ in bipartite bosonic systems, which satisfies $E_{\rm NG}=1$ for all Gaussian-entanglable states, while $E_{\rm NG}>1$ certifies non-Gaussian entanglement. Its ceiling $d=\lceil E_{\rm NG}\rceil$ provides a lower bound on the Schmidt number irreducible by Gaussian transformations, thereby defining a natural hierarchy of non-Gaussian entanglement. For pure states, the condition is sharp and the hierarchy reflects the complexity of state learning. We benchmark the framework with some paradigmatic non-Gaussian states, such as NOON states and squeezed Kerr states, and analyze its robustness against loss. Moreover, we construct an experimentally economical NOON-type witness requiring only four density-matrix element measurements. These results establish an operationally meaningful and experimentally accessible framework for identifying non-Gaussian entanglement resources in continuous-variable quantum platforms.
title Non-Gaussian Entanglement Hierarchy Based on the Schmidt Number
topic Quantum Physics
url https://arxiv.org/abs/2605.18605