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It is shown that any separable state on Hilbert space ${\cal H}={\cal H}_1\otimes{\cal H}_2$, can be written as a convex combination of N pure product states with $N\leq (dim{\cal H})^2$. Then a new separability criterion for mixed states…

Quantum Physics · Physics 2009-10-30 Pawel Horodecki

We study a separability problem suggested by mathematical description of bipartite quantum systems. We consider Hermitian 2-forms on the tensor product $H=K\otimes L$, where $K,L$ are finite dimensional complex spaces. Inspired by quantum…

Mathematical Physics · Physics 2010-01-11 Bronisław Jakubczyk , Gabriel Pietrzkowski

We introduce algebriac sets in the products of complex projective spaces for multipartite mixed states, which are independent of their eigenvalues and only measure the "position" of their eigenvectors, as their non-local invariants (ie.…

Quantum Physics · Physics 2007-05-23 Hao Chen

This paper present a geometric diagram of a separable state: If a mixed state $\sigma $ is separable, there are $2^{nS(\sigma)}$ linearly independant product vectors which span the same Hilbert space as the $2^{nS(\sigma)}$ ``likely''…

Quantum Physics · Physics 2007-05-23 Ping Xing Chen , Cheng Zu Li

The complete reducibility property for bipartite states reduced the separability problem to a proper subset of positive under partial transpose states and was used to prove several theorems inside and outside entanglement theory. So far…

Quantum Physics · Physics 2025-09-10 Daniel Cariello

With a probability of success of $95 \%$ we solve the separability problem for Bell diagonal qutrit states with positive partial transposition (PPT). The separability problem, i.e. distinguishing separable and entangled states, generally…

Quantum Physics · Physics 2022-09-22 Christopher Popp , Beatrix C. Hiesmayr

In this paper, we provide a complete mathematical theory for the entanglement of mixtures of Dicke states. These quantum states form an important subclass of bosonic states arising in the study of indistinguishable particles. We introduce a…

Quantum Physics · Physics 2026-02-18 Aabhas Gulati , Ion Nechita , Clément Pellegrini

We show that, in finite dimensions, around any $m$-partite product state $\rho_{\rm prod}=\rho_1\otimes...\otimes\rho_m$, there exists an ellipsoid of separable states centered around $\rho_{\rm prod}$. This separable ellipsoid contains the…

Quantum Physics · Physics 2025-07-30 Robin Y. Wen , Gilles Parez , Liuke Lyu , William Witczak-Krempa , Achim Kempf

We introduce a new technique to detect separable states using semidefinite programs. This approach provides a sufficient condition for separability of a state that is based on the existence of a certain local linear map applied to a known…

Quantum Physics · Physics 2009-11-13 Federico M. Spedalieri

We study the distinguishability of a particular type of maximally entangled states -- the "lattice states" using a new approach of semidefinite program. With this, we successfully construct all sets of four ququad-ququad orthogonal…

Quantum Physics · Physics 2019-04-03 Zong-Xing Xiong , Mao-Sheng Li , Zhu-Jun Zheng , Chuan-Jie Zhu , Shao-Ming Fei

It is known that he bipartite quantum states, with rank strictly smaller than the maximum of the ranks of its two reduced states, are distillable by local operations and classical communication. Our first main result is that this is also…

Quantum Physics · Physics 2015-05-27 Lin Chen , Dragomir Z. Djokovic

We study separability properties in a 5-dimensional set of states of quantum systems composed of three subsystems of equal but arbitrary finite Hilbert space dimension. These are the states, which can be written as linear combinations of…

Quantum Physics · Physics 2007-05-23 T. Eggeling , R. F. Werner

This paper develops a complete foundational treatment of simplicial complexes from Euclidean spaces through geometric realizations, emphasizing concrete computations, examples, and practical verification methods. Beginning with finite point…

Algebraic Topology · Mathematics 2025-12-02 Sanjay Mishra

We present a large class of indecomposable exposed positive linear maps between three dimensional matrix algebras. We also construct two qutrit separable states with lengths ten in the interior of their dual faces. With these examples, we…

Quantum Physics · Physics 2014-01-23 Kil-Chan Ha , Seung-Hyeok Kye

This paper is devoted to the study of the separability problem in the field of Quantum information theory. We deal mainly with the bipartite finite dimensional case and with two types of matrices, one of them being the PPT matrices. We…

Quantum Physics · Physics 2016-03-21 Daniel Cariello

Given any finite set of nonnegative integers, there exists a closed convex set whose facial dimension signature coincides with this set of integers, that is, the dimensions of its nonempty faces comprise exactly this set of integers. In…

Optimization and Control · Mathematics 2024-08-26 Vera Roshchina , Levent Tunçel

We construct three-qubit entanglement witnesses with the properties that all the partial transposes have the spanning properties. These witnesses determine faces for separable states whose interior lies in the interior of PPT states, and so…

Quantum Physics · Physics 2016-03-22 Seung-Hyeok Kye

We study extremality in various sets of states that have positive partial transposes. One of the tools we use for this purpose is the recently formulated criterion allowing to judge if a given state is extremal in the set of PPT states.…

Quantum Physics · Physics 2015-05-13 Remigiusz Augusiak , Janusz Grabowski , Marek Kuś , Maciej Lewenstein

We introduce a deformed product construction for simple polytopes in terms of lower-triangular block matrix representations. We further show how Gale duality can be employed for the construction and for the analysis of deformed products…

Metric Geometry · Mathematics 2012-12-27 Raman Sanyal , Günter M. Ziegler

We study separability properties in a 5-dimensional set of states of quantum systems composed of three subsystems of equal but arbitrary finite Hilbert space dimension d. These are the states, which can be written as linear combinations of…

Quantum Physics · Physics 2009-11-06 T. Eggeling , R. F. Werner