Contributors: Traitement optimal de l'information avec des dispositifs quantiques (QINFO); Inria Grenoble - Rhône-Alpes; Institut National de Recherche en Informatique et en Automatique (Inria)-Institut National de Recherche en Informatique et en Automatique (Inria)-École normale supérieure de Lyon (ENS de Lyon)-Université Claude Bernard Lyon 1 (UCBL); Université de Lyon-Université de Lyon-Université Grenoble Alpes (UGA)-Inria Lyon; Institut National de Recherche en Informatique et en Automatique (Inria); Probabilités, statistique, physique mathématique (PSPM); Institut Camille Jordan (ICJ); École Centrale de Lyon (ECL); Université de Lyon-Université de Lyon-Université Claude Bernard Lyon 1 (UCBL); Université de Lyon-Institut National des Sciences Appliquées de Lyon (INSA Lyon); Université de Lyon-Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Université Jean Monnet - Saint-Étienne (UJM)-Centre National de la Recherche Scientifique (CNRS)-École Centrale de Lyon (ECL); Université de Lyon-Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Université Jean Monnet - Saint-Étienne (UJM)-Centre National de la Recherche Scientifique (CNRS); University of Oslo (UiO); University of Siegen = Universität Siegen Siegen; ANR-20-CE47-0014,ESQuisses,Évolutions Stochastiques Quantiques(2020); European Project: 843414,TIPTOP; European Project: 683107,H2020,ERC-2015-CoG,TempoQ(2016)
نبذة مختصرة : International audience ; A separable quantum state shared between parties $A$ and $B$ can be symmetrically extended to a quantum state shared between party $A$ and parties $B_1,\ldots ,B_k$ for every $k\in\mathbf{N}$. Quantum states that are not separable, i.e., entangled, do not have this property. This phenomenon is known as "monogamy of entanglement". We show that monogamy is not only a feature of quantum theory, but that it characterizes the minimal tensor product of general pairs of convex cones $\mathsf{C}_A$ and $\mathsf{C}_B$: The elements of the minimal tensor product $\mathsf{C}_A\otimes_{\min} \mathsf{C}_B$ are precisely the tensors that can be symmetrically extended to elements in the maximal tensor product $\mathsf{C}_A\otimes_{\max} \mathsf{C}^{\otimes_{\max} k}_B$ for every $k\in\mathbf{N}$. Equivalently, the minimal tensor product of two cones is the intersection of the nested sets of $k$-extendible tensors. It is a natural question when the minimal tensor product $\mathsf{C}_A\otimes_{\min} \mathsf{C}_B$ coincides with the set of $k$-extendible tensors for some finite $k$. We show that this is universally the case for every cone $\mathsf{C}_A$ if and only if $\mathsf{C}_B$ is a polyhedral cone with a base given by a product of simplices. Our proof makes use of a new characterization of products of simplices up to affine equivalence that we believe is of independent interest.
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