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Characterization of quantum states and devices is paramount to quantum science and technology. The characterization consists of individual measurements, which must be precisely known. A mismatch between actual and assumed constituent…

Quantum Physics · Physics 2025-10-10 Robert Stárek , Martin Bielak , Miroslav Ježek

We consider the question of characterising the incompatibility of sets of high-dimensional quantum measurements. We introduce the concept of measurement incompatibility in subspaces. That is, starting from a set of measurements that is…

We study the compatibility (or joint measurability) of quantum observables in a setting where the experimenter has access to multiple copies of a given quantum system, rather than performing the experiments on each individual copy…

Quantum Physics · Physics 2016-09-14 Claudio Carmeli , Teiko Heinosaari , Daniel Reitzner , Jussi Schultz , Alessandro Toigo

This paper presents a philosophically realistic analysis of quantization, field-particle duality, superposition, entanglement, nonlocality, and measurement. These are logically related: Realistically understanding measurement depends on…

Quantum Physics · Physics 2019-07-30 Art Hobson

Quantum correlations in a physical system are usually studied with respect to a unique (fixed) decomposition of the system into subsystems, without fully exploiting the rich structure of the state-space. Here, we show several examples in…

Quantum Physics · Physics 2016-07-20 Guido Bellomo , Angelo Plastino , Angel R. Plastino

In this work, I propose a way to help high school students and the general population understand quantum concepts by adopting a new inherently dual representation. Major difficulties in explaining to people the basic concepts of quantum…

Popular Physics · Physics 2025-01-16 Gianluca Li Causi

We develop an original approach for the quantitative characterisation of the entanglement properties of, possibly mixed, bi- and multipartite quantum states of arbitrary finite dimension. Particular emphasis is given to the derivation of…

Quantum Physics · Physics 2009-11-11 Florian Mintert , Andre R. R. Carvalho , Marek Kus , Andreas Buchleitner

A cat state is a superposition of macroscopically distinct states. In quantum optics one such type of state is a superposition of distinct coherent states. Recently, a protocol has been proposed for preparing large optical cat states from a…

Quantum Physics · Physics 2007-05-23 Peter P. Rohde , Austin P. Lund

An universal approximation technique for analysis of different characteristics of states of composite infinite-dimensional quantum systems is proposed and used to prove general results concerning the properties of correlation and…

Quantum Physics · Physics 2024-11-01 M. E. Shirokov

Coherence arises from the superposition principle and plays a key role in quantum mechanics. Recently, Baumgratz et al. [T. Baumgratz, M. Cramer, and M. B. Plenio, Phys. Rev. Lett. 113, 140401 (2014)] established a rigorous framework for…

Quantum Physics · Physics 2016-03-23 Jianwei Xu

The rigorous resource framework of quantum coherence has been set up recently and excited a wide variety of interests. Here we show that a quantum cavity optomechanical system, as an emerging platform, can behave with a certain value of…

Quantum Physics · Physics 2016-12-21 Qiang Zheng , Jianwei Xu , Yao Yao , Yong Li

Some measurements in quantum mechanics disturb each other. This has puzzled physicists since the formulation of the theory, but only in recent decades has the incompatibility of measurements been analyzed in depth and detail, using the…

Quantum Physics · Physics 2023-02-14 Otfried Gühne , Erkka Haapasalo , Tristan Kraft , Juha-Pekka Pellonpää , Roope Uola

We review some applications of entanglement to improve quantum measurements and communication, with the main focus on the optical implementation of quantum information processing. The evolution of continuos variable entangled states in…

Quantum Physics · Physics 2007-05-23 M. G. A. Paris , G. M. D'Ariano , P. Lo Presti , P. Perinotti

We discuss the (re-)construction of quasiprobability representations from generic measurements, including noisy ones. Based on the measurement under study, quasiprobabilities and the associated concept of nonclassicality are introduced. A…

Quantum Physics · Physics 2025-11-07 Jan Sperling , Laura Ares , Elizabeth Agudelo

We consider in this paper the quantum limits for measurements on macroscopic bodies which are obtained in a novel way employing the concept of decoherence coming from an analysis of the quantum mechanics of dissipative systems. Two cases…

General Relativity and Quantum Cosmology · Physics 2009-10-22 Carlos O. Escobar , Lea Ferreira dos Santos , Paulo C. Marques

Targeting at the realization of scalable photonic quantum technologies, the generation of many photons, their propagation in large optical networks, and a subsequent detection and analysis of sophisticated quantum correlations are essential…

We study the stabilities of quantum states of macroscopic systems, against noises, against perturbations from environments, and against local measurements. We show that the stabilities are closely related to the cluster property, which…

Quantum Physics · Physics 2017-08-23 Akira Shimizu , Takayuki Miyadera , Akihisa Ukena

New measures for the quantization of systems with constraints are discussed and applied to several examples, in particular, examples of alternative but equivalent formulations of given first-class constraints, as well as a comparison of…

Quantum Physics · Physics 2007-05-23 John R. Klauder

We present a description of the measurement process based on the parametric representation with environmental coherent states. This representation is specifically tailored for studying quantum systems whose environment needs being…

Quantum Physics · Physics 2015-09-30 Pietro Liuzzo-Scorpo , Alessandro Cuccoli , Paola Verrucchi

The optical responses of solids are typically understood to be local in space. Whether locality holds for the optical response of a macroscopic quantum system has, however, been largely unexplored. Here, we use multidimensional coherent…