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We analyze the estimation of a qubit pure state by means of local measurements on $N$ identical copies and compare its averaged fidelity for an isotropic prior probability distribution to the absolute upper bound given by collective…

Quantum Physics · Physics 2009-11-10 E. Bagan , A. Monras , R. Munoz-Tapia

We present a single inequality as the necessary and sufficient condition for two unsharp observables of a two-level system to be jointly measurable in a single apparatus and construct explicitly the joint observables. A complementarity…

Quantum Physics · Physics 2008-09-17 Sixia Yu , Naile Liu , Li Li , C. H. Oh

We present a joint-measurement uncertainty relation for a pair of mean square deviations of canonical variables averaged over Gaussian distributed quantum optical states. Our Bayesian formulation is free from the unbiasedness assumption,…

Quantum Physics · Physics 2017-04-19 Ryo Namiki

In the following paper, we generalize the geometrical framework of qubit decoherence to higher dimensions. The quantum mixed state is represented by the probability distribution, which is the K\"ahler function on the projective Hilbert…

Mathematical Physics · Physics 2018-02-14 Katarzyna Siudzińska

Nonclassicality cannot be a single-observable property since the statistics of any quantum observable is compatible with classical physics. We develop a general procedure to reveal nonclassical behavior from the joint measurement of…

Quantum Physics · Physics 2016-05-04 Alfredo Luis

This paper addresses the question whether a variant of a modal interpretation is conceivable that could accommodate property ascriptions associated with nonorthogonal resolutions of the unity and nonorthogonal families of relative states as…

Quantum Physics · Physics 2007-05-23 P. Busch

In a Generalised Probabilistic Theory (GPT) equipped additionally with some extra geometric structure we define the morphophoric measurements as those for which the measurement map sending states to distributions of the measurement results…

Quantum Physics · Physics 2025-01-22 Anna Szymusiak , Wojciech Słomczyński

We provide a construction of sets of (d/2+1) mutually unbiased bases (MUBs) in dimensions d=4,8 using maximal commuting classes of Pauli operators. We show that these incomplete sets cannot be extended further using the operators of the…

Quantum Physics · Physics 2014-02-05 Prabha Mandayam , Somshubhro Bandyopadhyay , Markus Grassl , William K. Wootters

The aim of the paper is to extend the notion of $\alpha$-geometry in the classical and in the noncommutative case by introducing a more general class of pull-back metrics and to give concrete formulas for the scalar curvature of these…

Mathematical Physics · Physics 2008-01-23 Attila Andai

In quantum mechanics, the connection between the operator algebraic realization and the logical models of measurement of state observables has long been an open question. In the approach that is presented here, we introduce a new…

Quantum Physics · Physics 2023-06-12 Morrison Turnansky

Joint, or simultaneous, measurements of non-commuting observables are possible within quantum mechanics, if one accepts an increase in the variances of the jointly measured observables. In this paper, we discuss joint measurements of a spin…

Quantum Physics · Physics 2009-11-11 Erika Andersson , Stephen M. Barnett , Alain Aspect

The Measurement Based Quantum Computation (MBQC) model achieves universal quantum computation by employing projective single qubit measurements with classical feedforward on a highly entangled multipartite cluster state. Rapid advances in…

Quantum Physics · Physics 2021-12-23 Swapnil Nitin Shah

Determining the measurement uncertainty region is a difficult problem for generic sets of observables. For this reason the literature on exact measurement uncertainty regions is focused on symmetric sets of observables, where the symmetries…

Quantum Physics · Physics 2019-09-12 Oliver Reardon-Smith

A complete set of mutually unbiased bases in a Hilbert space of dimension $d$ defines a set of $d+1$ orthogonal measurements. Relative to such a set, we define a "MUB-balanced state" to be a pure state for which the list of probabilities of…

Quantum Physics · Physics 2015-06-22 Ilya Amburg , Roshan Sharma , Daniel Sussman , William K. Wootters

In prior work, we have shown how the basic concepts and terms of quantum mechanics relate to factorizations and marginals of complex-valued quantum mass functions, which are generalizations of joint probability mass functions. In this…

Quantum Physics · Physics 2019-10-08 Hans-Andrea Loeliger , Pascal O. Vontobel

Quantum sensors are expected to be a prominent use-case of quantum technologies, but in practice, noise easily degrades their performance. Quantum sensors can for instance be afflicted with erasure errors. Here, we consider using quantum…

Information Theory · Computer Science 2023-03-23 Yingkai Ouyang , Narayanan Rengaswamy

General characterization of physical measurements is discussed within the framework of a classical information theory. Uncertainty relation for simultaneous measurements of two physical observables is defined in this framework for…

Quantum Physics · Physics 2012-12-18 Yoshimasa Kurihara

Among the surprising features of quantum measurements, the problem of distinguishing and antidistinguishing general quantum measurements is fundamentally appealing. Unlike classical systems, quantum theory offers entangled states and…

Quantum Physics · Physics 2025-08-19 Satyaki Manna , Sneha Suresh , Manan Singh Kachhawaha , Debashis Saha

When an experimentalist measures a time series of qubits, the outcomes generate a classical stochastic process. We show that measurement induces high complexity in these processes in two specific senses: they are inherently unpredictable…

Quantum Physics · Physics 2020-10-14 Ariadna E. Venegas-Li , Alexandra M. Jurgens , James P. Crutchfield

We describe a particular class of pairs of quantum observables which are extremal in the convex set of all pairs of compatible quantum observables. The pairs in this class are constructed as uniformly noisy versions of two mutually unbiased…

Quantum Physics · Physics 2019-07-24 Claudio Carmeli , Gianni Cassinelli , Alessandro Toigo
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