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Mutually unbiased bases that can be cyclically generated by a single unitary operator are of special interest, since they can be readily implemented in practice. We show that, for a system of qubits, finding such a generator can be cast as…

Quantum Physics · Physics 2015-06-19 Ulrich Seyfarth , Luis L. Sanchez-Soto , Gerd Leuchs

We work out the phase-space structure for a system of $n$ qubits. We replace the field of real numbers that label the axes of the continuous phase space by the finite field $\Gal{2^n}$ and investigate the geometrical structures compatible…

Quantum Physics · Physics 2009-10-14 A. B. Klimov , J. L. Romero , G. Bjork , L. L. Sanchez-Soto

We use formal matrices whose entries we view as vector variables taking unit vectors values in one-qubit Hilbert spaces of a multiqubit quantum system. We construct many unextendible product bases (UPBs) of new sizes in such systems and…

Quantum Physics · Physics 2024-01-23 Lin Chen , Dragomir Z. Djokovic

We consider the problem of mutually unbiased bases as a polynomial optimization problem over the reals. We heavily reduce it using known symmetries before exploring it using two methods, combining a number of optimization techniques. The…

Quantum Physics · Physics 2023-08-04 Luke Mortimer

Based on maximally entangled states, we explore the constructions of mutually unbiased bases in bipartite quantum systems. We present a new way to construct mutually unbiased bases by difference matrices in the theory of combinatorial…

Quantum Physics · Physics 2022-10-05 Yajuan Zang , Zihong Tian , Hui-Juan Zuo , Shao-Ming Fei

Mutually unbiased bases (MUBs) are highly symmetric bases on complex Hilbert spaces, and the corresponding rank-1 projective measurements are ubiquitous in quantum information theory. In this work, we study a recently introduced…

Quantum Physics · Physics 2023-10-16 Máté Farkas , Jędrzej Kaniewski , Ashwin Nayak

The study of Mutually Unbiased Bases continues to be developed vigorously, and presents several challenges in the Quantum Information Theory. Two orthonormal bases in $\mathbb C^d, B {and} B'$ are said mutually unbiased if $\forall b\in B,…

Quantum Physics · Physics 2009-08-12 M. Combescure

This is a review of the problem of Mutually Unbiased Bases in finite dimensional Hilbert spaces, real and complex. Also a geometric measure of "mubness" is introduced, and applied to some recent calculations in six dimensions (partly done…

Quantum Physics · Physics 2015-06-26 Ingemar Bengtsson

I introduce a new notion, that extends the mutually unbiased bases (MUB) conditons to more than two bases. These, I call the nUB conditions, and the corresponding bases $n$-fold unbiased. They naturally appear while optimizing generic…

Quantum Physics · Physics 2017-06-15 Máté Farkas

We study mutually unbiased maximally entangled bases (MUMEB's) in bipartite system $\mathbb{C}^d\otimes\mathbb{C}^d (d \geq 3)$. We generalize the method to construct MUMEB's given in [16], by using any commutative ring $R$ with $d$…

Quantum Physics · Physics 2016-09-12 Junying Liu , Minghui Yang , Keqin Feng

We develop a general scheme for an analysis of macroscopic qudit systems: a) introduce a set of collective observables, which characterizes the macroscopic properties of qudits in an optimal way; b) construct projected $\tilde{Q}$-functions…

Quantum Physics · Physics 2020-06-24 C. Muñoz , I. Sainz , A. B. Klimov

The paper gives a short introduction to mutually unbiased bases and the Welch bounds and demonstrates that the latter is a good technical tool to explore the former. In particular, a criterion for a system of vectors to satisfy the Welch…

Quantum Physics · Physics 2008-07-22 Aleksandrs Belovs , Juris Smotrovs

In this paper, we explore the concept of Mutually Unbiased Bases (MUBs) in discrete quantum systems. It is known that for dimensions $d$ that are powers of prime numbers, there exists a set of up to $d+1$ bases that form an MUB set.…

The thesis is mainly about the construction and implementation of cyclic mutually unbiased bases, dealing with different entanglement structures by discussing the related group structures. A recursive construction for Fermat number…

Quantum Physics · Physics 2019-07-08 Ulrich Seyfarth

Construction of a large class of Mutually Unbiased Bases (MUBs) for non-prime power composite dimensions ($d = k\times s$) is a long standing open problem, which leads to different construction methods for the class Approximate MUBs (AMUBs)…

Discrete Mathematics · Computer Science 2024-02-07 Ajeet Kumar , Subhamoy Maitra

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

In quantum mechanics some properties are maximally incompatible, such as the position and momentum of a particle or the vertical and horizontal projections of a 2-level spin. Given any definite state of one property the other property is…

Quantum Physics · Physics 2009-11-13 A. J. Skinner , V. A. Newell , R. Sanchez

In this paper, we prove that the existence of a complete set of mutually unbiased bases (MUBs) in N-dimensional Hilbert space implies the existence of a complete set of mutually orthogonal Latin squares (MOLSs) of order N. In particular, we…

Quantum Physics · Physics 2026-01-26 Stefan Joka

Mutually unbiased bases (MUB) are an elusive discrete structure in Hilbert spaces. Many (complete sets of) MUB are group covariant, but little is known whether they can be sharply covariant in the sense that the generating groups can have…

Quantum Physics · Physics 2015-03-03 Huangjun Zhu

Mutually unbiased bases for quantum degrees of freedom are central to all theoretical investigations and practical exploitations of complementary properties. Much is known about mutually unbiased bases, but there are also a fair number of…

Quantum Physics · Physics 2019-03-04 Thomas Durt , Berthold-Georg Englert , Ingemar Bengtsson , Karol Życzkowski