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A measuring apparatus is described by quantum mechanics while it interacts with the quantum system under observation, and then it must be given a classical description so that the result of the measurement appears as objective reality.…

Quantum Physics · Physics 2009-10-30 Ori Hay , Asher Peres

Derivation and experimental violation of Bell-like inequalities involve the measurement of in-compatible observables. Simple complementarity forbids the existence of such joint probabilitydistribution. Moreover, the measurement of…

Quantum Physics · Physics 2020-06-18 Elisa Masa , Laura Ares , Alfredo Luis

At the heart of causal structure learning from observational data lies a deceivingly simple question: given two statistically dependent random variables, which one has a causal effect on the other? This is impossible to answer using…

Machine Learning · Computer Science 2020-10-13 Nikolaos Nikolaou , Konstantinos Sechidis

Our investigation of the results of the neutron spin experiment by Ehhart et al. demonstrates that their results cannot be understood in accordance with common sense. For example, their results obtained with different measurement errors are…

Quantum Physics · Physics 2013-09-10 Seiji Kosugi

What is the relation between spin squeezing and entanglement? To clarify this, we derive the full set of generalized spin squeezing inequalities for the detection of entanglement. These are inequalities for the mean values and variances of…

Quantum Physics · Physics 2009-05-08 Geza Toth , Christian Knapp , Otfried Gühne , Hans J. Briegel

In this article we exploit the Bhattacharyya statistical divergence to determine the similarity of probability distributions of quantum observables. After brief review of useful characteristics of the Bhattacharyya divergence we apply it to…

Statistical Mechanics · Physics 2009-11-07 V. Majernik , S. Shpyrko

In the weak measurement formalism of Y. Aharonov et al. the so-called weak value A_w of any observable A is generally a complex number. We derive a physical interpretation of its value in terms of the shift in the measurement pointer's mean…

Quantum Physics · Physics 2009-11-13 Richard Jozsa

Psychosocial constructs can only be assessed indirectly, and measures are typically formed by a combination of indicators that are thought to relate to the construct. Reflective and formative measurement models offer different…

Methodology · Statistics 2021-02-24 Tyler J. VanderWeele

Several definitions for the average local value and local variance of a quantum observable are examined and compared with their classical counterparts. An explicit way to construct an infinite number of these quantities is provided. It is…

Quantum Physics · Physics 2009-10-31 J. G. Muga , J. P. Palao , R. Sala

We analyze different data of the variation of the fine structure constant obtained with different methods to check their consistency.We test consistency using the modified Student test and confidence intervals. We split the data sets in…

Astrophysics · Physics 2009-11-13 Susana J. Landau , Claudio Simeone

In his Comment on a recent paper by two of us Kominis claims that the recently proposed quantum measurement model for spin-selective reactions of radical pairs leads to ambiguous predictions in a simple case. Here we show that this claim is…

Quantum Physics · Physics 2011-05-09 J. A. Jones , Kiminori Maeda , U. E. Steiner , P. J. Hore

Weak measurements have an increasing number of applications in contemporary quantum mechanics. They were originally described as a weak interaction that slightly entangled the translational degrees of freedom of a particle to its spin,…

We study causal inference in experiments and quasi-experiments, where the economic outcome is imperfectly measured by a remotely sensed variable. The remotely sensed variable is low-cost, scalable, and predictive of the economic outcome in…

Econometrics · Economics 2026-05-20 Ashesh Rambachan , Rahul Singh , Davide Viviano

Physical systems may couple to other systems through variables that are not gauge invariant. When we split a gauge system into two subsystems, the gauge-invariant variables of the two subsystems have less information than the gauge…

High Energy Physics - Theory · Physics 2021-04-14 Carlo Rovelli

Traditional mathematical notation can lead to confusion. Expressions that appear to define composite functions sometimes do not. A particular example with engineering applications is studied in detail.

History and Overview · Mathematics 2016-01-21 Harold P. Boas

This study shows that typical pendulum dynamics is far from the simple equation of motion presented in textbooks. A reasonably complete damping model must use nonlinear terms in addition to the common linear viscous expression. In some…

Classical Physics · Physics 2007-05-23 Randall D. Peters

We investigate the role of coherence and Markovianity in finding an answer to the question whether the outcomes of a projectively measured quantum stochastic process are compatible with a classical stochastic process. For this purpose we…

Quantum Physics · Physics 2019-08-20 Philipp Strasberg , María García Díaz

Hidden-variable models aim to reproduce the results of quantum theory and to satisfy our classical intuition. Their refutation is usually based on deriving predictions that are different from those of quantum mechanics. Here instead we…

Quantum Physics · Physics 2015-03-05 Radu Ionicioiu , Robert B. Mann , Daniel R. Terno

Bell's theorem states that quantum correlation function of two spins can not be represented as an expectation value of two classical random variables. Spin is described in Bell's model by a single scalar random variable. We discuss another…

Quantum Physics · Physics 2007-05-23 Igor Volovich , Yaroslav Volovich

Since weak measurements are known to produce measurement values that can be much larger than the maximal eigenvalues of the measured observable, it is an interesting question how this enhancement of the measurement signal relates to the…

Quantum Physics · Physics 2012-11-21 Holger F. Hofmann