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The notion coexistence of quantum observables was introduced to describe the possibility of measuring two or more observables together. Here we survey the various different formalisations of this notion and their connections. We review…

Quantum Physics · Physics 2011-01-04 P. Busch , J. Kiukas , P. Lahti

We compute the Hall angle and the magnetoresistance of the spin-fermion model, which is a successful phenomenological theory to describe the physics of the cuprates and iron-based superconductors within a wide range of doping regimes. We…

Strongly Correlated Electrons · Physics 2017-09-04 Hermann Freire

We summarise important recent advances in quantum metrology, in connection to experiments in cold gases, trapped cold atoms and photons. First we review simple metrological setups, such as quantum metrology with spin squeezed states, with…

Quantum Physics · Physics 2015-01-27 Geza Toth , Iagoba Apellaniz

The quantum measurement incompatibility is a distinctive feature of quantum mechanics. We investigate the incompatibility of a set of general measurements and classify the incompatibility by the hierarchy of compatibilities of its subsets.…

Quantum Physics · Physics 2020-02-03 Bao-Zhi Sun , Zhi-Xi Wang , Xianqing Li-Jost , Shao-Ming Fei

Quantum estimation involving multiple parameters remains an important problem of both theoretical and practical interest. In this work, we study the problem of simultaneous estimation of two parameters that are respectively associate with…

Quantum Physics · Physics 2022-03-25 Yink Loong Len

Wigner's friend paradoxes highlight contradictions between measurements made by Friends inside a laboratory and superobservers outside a laboratory, who have access to an entangled state of the measurement apparatus. The contradictions lead…

This article presents a full operator analytical method for studying the quadratic nonlinear interactions in quantum optomechanics. The method is based on the application of higher-order operators, using a six-dimensional basis of second…

Quantum Physics · Physics 2018-11-13 Sina Khorasani

Violation of the CHSH inequality by a bipartite quantum state is now used in many quantum applications. However, the explicit analytical expression for the maximal value of the CHSH expectation under local Alice and Bob spin-$s$…

Quantum Physics · Physics 2025-08-11 Elena R. Loubenets , Louis Hanotel

Macroscopic observables in a quantum spin system are given by sequences of spatial means of local elements $\frac{1}{2n+1}\sum_{j=-n}^n\gamma_j(A_{i}), \; n\in{\mathbb N},\; i=1,...,m$ in a UHF algebra. One of their properties is that they…

Operator Algebras · Mathematics 2013-04-03 Yoshiko Ogata

Quantum mechanics violates Leggett-Garg inequalities because the operator formalism predicts correlations between different spin components that would correspond to negative joint probabilities for the outcomes of joint measurements.…

Quantum Physics · Physics 2015-03-20 Yutaro Suzuki , Masataka Iinuma , Holger F. Hofmann

We list in increasing order -- 1/3, 3/8, 2/5, 135 pi/1024, 16/(3 pi^2), 3 pi/16, 5/8, 105 pi/512, 2 - 435 pi/1024, 11/16, 1 -- a number of exact two-qubit Hilbert-Schmidt (HS) separability probabilities, we are able to compute. Each…

Quantum Physics · Physics 2007-05-23 Paul B. Slater

Quasisymmetric stellarators are an attractive class of optimised magnetic confinement configurations. The property of quasisymmetry (QS) is in practice limited to be approximate, and thus the construction requires measures that quantify the…

Plasma Physics · Physics 2022-02-16 Eduardo Rodriguez , Elizabeth Paul , Amitava Bhattacharjee

The integral of the Wigner function of a quantum mechanical system over a region or its boundary in the classical phase plane, is called a quasiprobability integral. Unlike a true probability integral, its value may lie outside the interval…

Quantum Physics · Physics 2009-11-10 A. J. Bracken , D. Ellinas , J. G. Wood

(Quasi)conformal scaling of composite operators from a strongly coupled EWSB dynamics helps to produce the characteristic hierarchies exhibited by the flavour couplings of the SM. It is however crucial to ensure that specific models satisfy…

High Energy Physics - Lattice · Physics 2013-11-19 Luigi Del Debbio , Liam Keegan , Carlos Pena

Aims. The main purpose of this work is to provide a method to derive tabulated observational constraints on the halo mass function (HMF) by studying the magnification bias effect on high-redshift submillimeter galaxies. Under the assumption…

Cosmology and Nongalactic Astrophysics · Physics 2021-02-09 M. M. Cueli , L. Bonavera , J. González-Nuevo , A. Lapi

We study the stability of the Quantum Critical Point (QCP) for itinerant ferromagnets commonly described by the Hertz-Millis-Moriya (HMM) theory. We argue that in $D \leq 3$, long-range spatial correlations associated with the Landau…

Strongly Correlated Electrons · Physics 2011-04-04 Andrey V. Chubukov , Catherine Pépin , Jerome Rech

A measurement model is a framework that describes a quantum measurement process. In this article we restrict attention to $MM$s on finite-dimensional Hilbert spaces. Suppose we want to measure an observable $A$ whose outcomes $A_x$ are…

Quantum Physics · Physics 2020-09-29 Stan Gudder

Orbital and spin ordering phenomena in strongly correlated systems are commonly studied using the local-density approximation + dynamical mean-field theory approach. Typically, however, such simulations are restricted to simplified models…

Strongly Correlated Electrons · Physics 2014-04-28 Andreas Flesch , Evgeny Gorelov , Erik Koch , Eva Pavarini

We determine the quantum states and measurements that optimize the accessible information in a reference frame alignment protocol associated with the groups U(1), corresponding to a phase reference, and $\mathbb{Z}_M$, the cyclic group of…

Quantum Physics · Physics 2012-07-17 Michael Skotiniotis , Gilad Gour

Majorization uncertainty relations are derived for arbitrary quantum operations acting on a finite-dimensional space. The basic idea is to consider submatrices of block matrices comprised of the corresponding Kraus operators. This is an…

Quantum Physics · Physics 2016-08-02 Alexey E. Rastegin , Karol Życzkowski