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In this work are presented sets of projectors for reconstruction of a density matrix for an arbitrary mixed state of a quantum system with the finite-dimensional Hilbert space. It was discussed earlier [quant-ph/0104126] a construction with…

Quantum Physics · Physics 2007-05-23 Alexander Yu. Vlasov

It is well known that an (in general, non-commutative) set of non-Hermitian operators $\Lambda_j$ with real eigenvalues need not necessarily represent observables. We describe a specific class of quantum models in which these operators plus…

Quantum Physics · Physics 2022-08-02 Miloslav Znojil

Maximal sets of mutually unbiased bases are useful throughout quantum physics, both in a foundational context and for applications. To date, it remains unknown if complete sets of mutually unbiased bases exist in Hilbert spaces of…

Quantum Physics · Physics 2026-04-09 Daniel McNulty , Stefan Weigert

We review the idea of Hilbert Series as a tool to study the moduli space and the BPS operators of four dimensional N=1 supersymmetric field theories. We concentrate on the particular case of N=1 superconformal field theories living on N D3…

High Energy Physics - Theory · Physics 2010-11-11 Davide Forcella

In quantum information theory, it is a fundamental problem to construct multipartite unextendible product bases (UPBs). We show that there exist two families UPBs in Hilbert space…

Quantum Physics · Physics 2022-12-06 Yize Sun , Baoshan Wang , Shiru Li

A discussion of discrete Wigner functions in phase space related to mutually unbiased bases is presented. This approach requires mathematical assumptions which limits it to systems with density matrices defined on complex Hilbert spaces of…

Quantum Physics · Physics 2009-11-11 Arthur O. Pittenger , Morton H. Rubin

Mutually unbiased bases are an important tool in many applications of quantum information theory. We present a new algorithm for finding the mutually unbiased bases for two-qubit systems. We derive a system of four equations in the Galois…

Quantum Physics · Physics 2014-01-06 Iulia Ghiu

A Galois unitary is a generalization of the notion of anti-unitary operators. They act only on those vectors in Hilbert space whose entries belong to some chosen number field. For Mutually Unbiased Bases the relevant number field is a…

Quantum Physics · Physics 2014-11-03 D. M. Appleby , Ingemar Bengtsson , Hoan Bui Dang

We study measurements of the unitary generalization of Pauli operators. First, an analytical (constructive) solution to the eigenproblem of these operators is presented. Next, in the case of two subsystems, the Schmidt form of the…

Quantum Physics · Physics 2009-11-13 Tomasz Paterek

Quantum dense coding plays an important role in quantum cryptography communication, and how to select a set of appropriate unitary operators to encode message is the primary work in the design of quantum communication protocols. Shukla et…

Quantum Physics · Physics 2024-05-14 Wenjie Liu , Junxiu Chen , Wenbin Yu , Zhihao Liu , Hanwu Chen

Just as any state of a single qubit or 2-level system can be obtained from any other state by a rotation operator parametrized by three real Euler angles, we show how any state of an n-qubit or 2^n-level system can be obtained from any…

Quantum Physics · Physics 2007-05-23 W. E. Baylis , R. Cabrera , C. Rangan

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

We introduce an approach for estimating the expectation values of arbitrary $n$-qubit matrices $M \in \mathbb{C}^{2^n\times 2^n}$ on a quantum computer. In contrast to conventional methods like the Pauli decomposition that utilize $4^n$…

Quantum Physics · Physics 2024-05-07 Dingjie Lu , Yangfan Li , Dax Enshan Koh , Zhao Wang , Jun Liu , Zhuangjian Liu

Let $n$ be any natural number. The $n$-centered operator is introduced for adjointable operators on Hilbert $C^*$-modules. Based on the characterizations of the polar decomposition for the product of two adjointable operators, $n$-centered…

Operator Algebras · Mathematics 2018-07-16 Na Liu , Wei Luo , Qingxiang Xu

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

In the last years, we have been witnessing a tremendous push to demonstrate that quantum computers can solve classically intractable problems. This effort, initially focused on the hardware, progressively included the simplification of the…

Quantum Physics · Physics 2024-01-26 Lane G. Gunderman , Andrew J. Jena , Luca Dellantonio

Analysis of quantum processes, especially in the context of noise, errors, and decoherence is essential for the improvement of quantum devices. An intuitive representation of those processes modeled by quantum channels are Pauli transfer…

Quantum Physics · Physics 2025-07-25 Lukas Hantzko , Lennart Binkowski , Sabhyata Gupta

Based on local unitary operators acting on a n-dimensional Hilbert-space, we investigate selective and collective operator basis sets for N-particle quantum networks. Selective cluster operators are used to derive the properties of general…

Quantum Physics · Physics 2009-11-07 Alexander Otte , Guenter Mahler

Contents 1. Creation and annihilation operators for the system of indistinguishable particles 1.1 The permutation group and the states of a system of indistinguishable particles 1.2 Dimension of the Hilbert space of a system of…

Quantum Gases · Physics 2013-08-16 V. S. Shchesnovich

The aim of the present paper is, firstly we study the concepts of (m, (q_1, ..., q_d))- partial isometries on a Hilbert space, secondly, we introduce the notion of m- invertibility of tuples of operators as a natural generalization of the…

Functional Analysis · Mathematics 2016-03-01 Ould Ahmed Mahmoud Sid Ahmed