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The unextendible product basis (UPB) is generalized to the unextendible entangled basis with any arbitrarily given Schmidt number $k$ (UEBk) for any bipartite system $\mathbb{C}^d\otimes\mathbb{C}^{d'}$ ($2\leq k<d\leq d'$), which can also…

Quantum Physics · Physics 2014-11-21 Yu Guo , Shengjun Wu

Unextendible product bases (UPBs) provide a versatile tool with various applications across different areas of quantum information theory. Their comprehensive characterization is thus of great importance and has been a subject of vital…

Quantum Physics · Physics 2022-08-24 Maciej Demianowicz

Unextendible product bases (UPBs) are interesting mathematical objects arising in composite Hilbert spaces that have found various applications in quantum information theory, for instance in a construction of bound entangled states or Bell…

Quantum Physics · Physics 2018-07-16 Maciej Demianowicz , Remigiusz Augusiak

Mutually unbiased bases (MUBs), which are such that the inner product between two vectors in different orthogonal bases is a constant equal to 1/sqrt{d), with d the dimension of the finite Hilbert space, are becoming more and more studied…

Quantum Physics · Physics 2009-11-11 M. Planat , H. C. Rosu

A set of orthogonal pure states is an unextendible biseparable basis (UBB), which means that its complementary subspace contains only genuinely entangled states. UBBs thus serve as an effective tool for constructing genuinely entangled…

Quantum Physics · Physics 2026-03-11 Huaqi Zhou , Ting Gao , Fengli Yan

We introduce qustochastic matrices as the bistochastic matrices arising from quaternionic unitary matrices by replacing each entry with the square of its norm. This is the quaternionic analogue of the unistochastic matrices studied by…

Mathematical Physics · Physics 2009-03-18 Oleg Chterental , Dragomir Z. Djokovic

In quantum mechanics, mutually unbiased bases (MUBs) represent orthonormal bases that are as "far apart" as possible, and their classification reveals rich underlying geometric structure. Given a complex inner product space, we construct…

Mathematical Physics · Physics 2025-08-22 Amit Te'eni , Eliahu Cohen

Mutually Unbiased Bases (MUBs) are closely connected with quantum physics, and the structure has a rich mathematical background. We provide equivalent criteria for extending a set of MUBs for $C^n$ by studying real points of a certain…

Discrete Mathematics · Computer Science 2025-07-04 Arindam Banerjee , Kanoy Kumar Das , Ajeet Kumar , Rakesh Kumar , Subhamoy Maitra

Mutually unbiased bases (MUBs) play a crucial role in numerous applications within quantum information science, such as quantum state tomography, error correction, entanglement detection, and quantum cryptography. Utilizing \(2^n + 1\) MUB…

Quantum Physics · Physics 2024-07-22 Wang Yu , Wu Dongsheng

In this work we present a method of decomposition of arbitrary unitary matrix $U\in\mathbf U(2^k)$ into a product of single-qubit negator and controlled-$\sqrt{\mbox{NOT}}$ gates. Since the product results with negator matrix, which can be…

Quantum Physics · Physics 2016-10-27 Adam Glos , Przemysław Sadowski

Analysis of state reconstruction both classical and quantum mechanical on equal footing is outlined. The meaning of "mutual unbiased bases" (MUB) of Hilbert spaces is explained in detail. An alternative quantum state reconstruction, that…

Quantum Physics · Physics 2009-12-31 M. Revzen

This short note highlights the most prominent mathematical problems and physical questions associated with the existence of the maximum sets of mutually unbiased bases (MUBs) in the Hilbert space of a given dimension

Quantum Physics · Physics 2009-11-10 H. C. Rosu , M. Planat , M. Saniga

We present a detailed computational and algebraic study of Mutually Unbiased Bases (MUBs) in finite-dimensional Hilbert spaces, with a particular focus on dimensions 2, 3, 4, and the challenging case of 6. Starting from the Hadamard-phase…

Quantum Physics · Physics 2026-04-03 Jean-Christophe Pain

Mutually unbiased bases (MUBs), which are such that the inner product between two vectors in different orthogonal bases is constant equal to the inverse $1/\sqrt{d}$, with $d$ the dimension of the finite Hilbert space, are becoming more and…

Quantum Physics · Physics 2009-11-11 Michel Planat , Haret Rosu

For the 3-qubit UPB state, i.e., the bound entangled state constructed from an Unextendable Product Basis of Bennett et al. (Phys. Rev. Lett. 82:5385, 1999), we provide a set of violations of Local Hidden Variable (LHV) models based on the…

Quantum Physics · Physics 2007-05-23 Claudio Altafini

Mutually Unbiased Bases (MUBs) constitute a fundamental geometric structure in quantum theory, known for providing an optimal measurement scheme for quantum state tomography. In prime and prime-power dimensions, analytical constructions of…

Quantum Physics · Physics 2026-04-07 Buğra Gültekin , Solomon B. Samuel , Zafer Gedik

We introduce the concept of n-OU and n-OO matrix sets, a collection of n mutually-orthogonal unitary and real orthogonal matrices under Hilbert-Schmidt inner product. We give a detailed characterization of order-three n-OO matrix sets under…

Quantum Physics · Physics 2025-10-28 Zhiwei Song , Lin Chen , Saiqi Liu

We generalize the concept of mutually unbiased bases (MUB) to measurements which are not necessarily described by rank one projectors. As such, these measurements can be a useful tool to study the long standing problem of the existence of…

Quantum Physics · Physics 2015-06-18 Amir Kalev , Gilad Gour

A few simply-stated rules govern the entanglement patterns that can occur in mutually unbiased basis sets (MUBs), and constrain the combinations of such patterns that can coexist (ie, the stoichiometry) in full complements of p^N+1 MUBs. We…

Quantum Physics · Physics 2013-05-29 Jay Lawrence

We study genuine tripartite entanglement and multipartite entanglement in arbitrary $n$-partite quantum systems based on complete orthogonal basis (COB). While the usual Bloch representation of a density matrix uses three types of…

Quantum Physics · Physics 2024-02-21 Hui Zhao , Jia Hao , Jing Li , Shao-Ming Fei , Naihuan Jing , Zhi-Xi Wang