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Higher dimensional entangled states demonstrate significant advantages in quantum information processing tasks. Schmidt number is a quantity on the entanglement dimension of a bipartite state. Here we build families of k-positive maps from…

Quantum Physics · Physics 2024-03-04 Xian Shi

We investigate global locations of Schmidt number witnesses which are outside of the convex set of all bipartite states. Their locations are classified by interiors of faces of the convex set of all states, by considering the line segments…

Quantum Physics · Physics 2025-09-16 Kyung Hoon Han , Seung-Hyeok Kye

We apply the generalised concept of witness operators to arbitrary convex sets, and review the criteria for the optimisation of these general witnesses. We then define an embedding of state vectors and operators into a higher-dimensional…

Quantum Physics · Physics 2007-05-23 Florian Hulpke , Dagmar Bruss , Maciej Lewenstein , Anna Sanpera

The Schmidt number is an important kind of characterization of quantum entanglement. Quantum states with higher Schmidt numbers demonstrate significant advantages in various quantum information processing tasks. By deriving a class of…

Quantum Physics · Physics 2025-11-18 Xiao-Qian Mu , Hao-Fan Wang , Shao-Ming Fei

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

We introduce the notion of a Schmidt number of a bipartite density matrix, characterizing the minimum Schmidt rank of the pure states that are needed to construct the density matrix. We prove that Schmidt number is nonincreasing under local…

Quantum Physics · Physics 2009-10-31 Barbara M. Terhal , Pawel Horodecki

It is shown that for each mixed state there exists a Schmidt (super state vector) decomposition in terms of Hermitian operators. Its utilization for finding all twins is illustrated in full detail in the case of the two…

Quantum Physics · Physics 2009-11-10 F. Herbut

A profound comprehension of quantum entanglement is crucial for the progression of quantum technologies. The degree of entanglement can be assessed by enumerating the entangled degrees of freedom, leading to the determination of a parameter…

Quantum Physics · Physics 2025-04-16 Liang Xiong , Nung-sing Sze

Entanglement witnesses (EWs) are fundamental tools for detecting entanglement. However traditional linear witnesses often fail to identify most of the entangled states. In this work, we construct a family of nonlinear entanglement witnesses…

Quantum Physics · Physics 2025-12-05 AmirHossein Tangestaninejad , Vahid Karimipour

We study Schmidt rank for a vector (i.e., a pure state) and Schmidt number for a mixed state which are entanglement measures. We show that if a subspace of a certain bipartite system contains no vector of Schmidt rank $\leqslant k$, then…

Quantum Physics · Physics 2018-04-13 Priyabrata Bag , Santanu Dey

The Schmidt number is a fundamental parameter characterizing the properties of quantum states, and the local projections are a fundamental operation in quantum physics. We investigate the relation between the Schmidt numbers of bipartite…

Quantum Physics · Physics 2016-09-19 Lin Chen , Yu Yang , Wai-shing Tang

Werner states are multipartite quantum states that are invariant under the diagonal conjugate action of the unitary group. This paper gives a complete characterization of their entanglement that is independent of the underlying local…

Quantum Physics · Physics 2022-11-22 Felix Huber , Igor Klep , Victor Magron , Jurij Volčič

Recent progress in quantum optics has led to setups that are able to prepare high-dimensional quantum states for quantum information processing tasks. As such, it is of importance to benchmark the states generated by these setups in terms…

Quantum Physics · Physics 2023-03-03 Nikolai Wyderka , Giovanni Chesi , Hermann Kampermann , Chiara Macchiavello , Dagmar Bruß

Schmidt decomposition is a powerful tool in quantum information. While Schmidt decomposition is universal for bipartite states, its not for multipartite states. In this article, we review properties of bipartite Schmidt decompositions and…

Quantum Physics · Physics 2025-02-15 Mithilesh Kumar

We consider bi-linear analogues of $s$-positivity for linear maps. The dual objects of these notions can be described in terms of Schimdt ranks for tri-tensor products and Schmidt numbers for tri-partite quantum states. These tri-partite…

Quantum Physics · Physics 2016-03-22 Kyung Hoon Han , Seung-Hyeok Kye

In quantum information theory, the Schmidt rank is a fundamental measure for the entanglement dimension of a pure bipartite state. Its natural definition uses the Schmidt decomposition of vectors on bipartite Hilbert spaces, which does not…

Quantum Physics · Physics 2024-06-21 Lauritz van Luijk , René Schwonnek , Alexander Stottmeister , Reinhard F. Werner

In this study, we enhance the understanding of entanglement transformations and their quantification by extending the concept of Schmidt vector from pure to mixed bipartite states, exploiting the lattice structure of majorization. The…

Quantum Physics · Physics 2024-07-25 F. Meroi , M. Losada , G. M. Bosyk

We present a survey on mathematical topics relating to separable states and entanglement witnesses. The convex cone duality between separable states and entanglement witnesses is discussed and later generalized to other families of…

Quantum Physics · Physics 2011-01-24 Lukasz Skowronek

For any bipartite quantum system the Schmidt decomposition allows us to express the state vector in terms of a single sum instead of double sums. We show the existence of the Schmidt decomposition for tripartite system under certain…

Quantum Physics · Physics 2009-10-31 Arun K. Pati

Positive maps which are not completely positive are used in quantum information theory as witnesses for convex sets of states, in particular as entanglement witnesses and more generally as witnesses for states having Schmidt number not…

Quantum Physics · Physics 2007-12-17 Kedar S. Ranade , Mazhar Ali
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