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We use the language of semidefinite programming and duality to derive necessary and sufficient conditions for the optimal Lewenstein-Sanpera Decomposition (LSD) of 2-qubit states. We first provide a simple and natural derivation of the…

Quantum Physics · Physics 2010-07-28 Guo Chuan Thiang , Philippe Raynal , Berthold-Georg Englert

High-dimensional entanglement, captured by the Schmidt number, underpins advantages in quantum information tasks, yet a unified resource-theoretic description across different Buscemi-type operational objects has been missing. Here we…

Quantum Physics · Physics 2025-12-30 Xian Shi

The Schmidt number of a mixed state characterizes the minimum Schmidt rank of the pure states needed to construct it. We investigate the Schmidt number of an arbitrary mixed state by constructing a Schmidt number witness that detects it. We…

Quantum Physics · Physics 2009-11-06 Anna Sanpera , Dagmar Bruss , Maciej Lewenstein

Understanding the structure of multi-qubit quantum states is essential for both quantum information research and education, yet intuitive visualization beyond the single-qubit Bloch sphere remains challenging. In this work, we propose a…

Quantum Physics · Physics 2026-03-11 Satoru Shoji

The Schmidt-decomposition formalism is proposed to be used for evaluation of the degree of quadrature entanglement in two-mode multiphoton states.

Quantum Physics · Physics 2020-04-22 Mikhail Fedorov

We study the invariants of arbitrary dimensional multipartite quantum states under local unitary transformations. For multipartite pure states, we give a set of invariants in terms of singular values of coefficient matrices. For…

Quantum Physics · Physics 2015-09-04 Ting-Gui Zhang , Ming-Jing Zhao , Xianqing Li-Jost , Shao-Ming Fei

An input-output model of a two-level quantum system in the Heisenberg picture is of bilinear form with constant system matrices, which allows the introduction of the concepts of controllability and observability in analogy with those of…

Quantum Physics · Physics 2019-09-18 Guofeng Zhang , Ian R. Petersen

We provide a graphical description of the entanglement of pure-state multiparty systems based on an analogy between a bipartite purity analysis and the centroid of a collection of point masses. This description applies to quantum systems…

Quantum Physics · Physics 2016-10-12 Miguel A. Alonso , Xiao-Feng Qian , J. H. Eberly

We study the local unitary equivalence of arbitrary dimensional multipartite quantum mixed states. We present a necessary and sufficient criterion of the local unitary equivalence for general multipartite states based on matrix realignment.…

Quantum Physics · Physics 2015-06-17 Ting-Gui Zhang , Ming-Jing Zhao , Ming Li , Shao-Ming Fei , Xianqing Li-Jost

The new method of multivariate data analysis based on the complements of classical probability distribution to quantum state and Schmidt decomposition is presented. We considered Schmidt formalism application to problems of statistical…

Quantum Physics · Physics 2017-01-10 Yu. I. Bogdanov , N. A. Bogdanova , D. V. Fastovets , V. F. Luckichev

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

For a finite dimensional discrete bipartite system, we find the relation between local projections performed by Alice, and Bob post-selected state dependence on the global state submatrices. With this result the joint state reconstruction…

Quantum Physics · Physics 2015-05-13 F. E. S. Steinhoff , M. C. de Oliveira

We study the separability of bipartite quantum systems in arbitrary dimensions using the Bloch representation of their density matrix. This approach enables us to find an alternative characterization of the separability problem, from which…

Quantum Physics · Physics 2024-12-05 Julio I. de Vicente

We analyze the distinguishability norm on the states of a multi-partite system, defined by local measurements. Concretely, we show that the norm associated to a tensor product of sufficiently symmetric measurements is essentially equivalent…

Quantum Physics · Physics 2013-09-17 Cécilia Lancien , Andreas Winter

We show that several classes of mixed quantum states in finite-dimensional Hilbert spaces which can be characterized as being, in some respect, 'most classical' can be described and analyzed in a unified way. Among the states we consider…

Quantum Physics · Physics 2013-05-29 Marek Kuś , Ingemar Bengtsson

The amount of entanglement that exists in a parametric down-converted state is investigated in terms of all the degrees of freedom of the state. We quantify the amount of entanglement by the Schmidt number of the state, represented as a…

Quantum Physics · Physics 2020-05-13 Filippus S. Roux

We investigate quantumness of spin-1 states, defined as the Hilbert-Schmidt distance to the convex hull of spin coherent states. We derive its analytic expression in the case of pure states as a function of the smallest eigenvalue of the…

Quantum Physics · Physics 2016-01-13 Fabian Bohnet-Waldraff , Daniel Braun , Olivier Giraud

Determining the relationship between composite systems and their subsystems is a fundamental problem in quantum physics. In this paper we consider the spectra of a bipartite quantum state and its two marginal states. To each spectrum we can…

Quantum Physics · Physics 2007-05-23 Matthias Christandl , Graeme Mitchison

In this paper we study the entanglement in symmetric $N$-quDit systems. In particular we use generalizations to $U(D)$ of spin $U(2)$ coherent states and their projections on definite parity $\mathbb{C}\in\mathbb{Z}_2^{D-1}$ (multicomponent…

Quantum Physics · Physics 2026-02-06 Julio Guerrero , Antonio Sojo , Alberto Mayorgas , Manuel Calixto

Entanglement of pure states of bipartite quantum systems has been shown to have a unique measure in terms of the von Neumann entropy of the reduced states of either of its subsystems. The measure is established under entanglement…

Quantum Physics · Physics 2007-05-23 Garry Bowen , Nilanjana Datta