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Within the framework of generalized noncontextuality, we introduce a general technique for systematically deriving noncontextuality inequalities for any experiment involving finitely many preparations and finitely many measurements, each of…

Quantum Physics · Physics 2021-06-16 David Schmid , Robert W. Spekkens , Elie Wolfe

A common assumption in causal inference from observational data is that there is no hidden confounding. Yet it is, in general, impossible to verify this assumption from a single dataset. Under the assumption of independent causal mechanisms…

Methodology · Statistics 2023-11-07 Rickard K. A. Karlsson , Jesse H. Krijthe

Quantum correlations are contextual yet, in general, nothing prevents the existence of even more contextual correlations. We identify and test a noncontextuality inequality in which the quantum violation cannot be improved by any…

The existence of observables that are incompatible or not jointly measurable is a characteristic feature of quantum mechanics, which lies at the root of a number of nonclassical phenomena, such as uncertainty relations, wave--particle dual…

Quantum Physics · Physics 2015-11-17 Huangjun Zhu

We consider a quantum system that is being continuously monitored, giving rise to a measurement signal. From such a stream of data, information needs to be inferred about the underlying system's dynamics. Here we focus on hypothesis testing…

Quantum Physics · Physics 2024-03-27 Giulio Gasbarri , Matias Bilkis , Elisabet Roda-Salichs , John Calsamiglia

Various local hidden variables models for the singlet correlations exploit the detection loophole, or other loopholes connected with post-selection on coincident arrival times. I consider the connection with a probabilistic simulation…

Quantum Physics · Physics 2007-05-23 Richard D. Gill

Generalized noncontextuality is a well-studied notion of classicality that is applicable to a single system, as opposed to Bell locality. It relies on representing operationally indistinguishable procedures identically in an ontological…

Quantum Physics · Physics 2025-01-13 Victor Gitton , Mischa P. Woods

This paper deals with three traditional ways of defining contextuality: (C1) in terms of (non)existence of certain joint distributions involving measurements made in several mutually exclusive contexts; (C2) in terms of relationship between…

Quantum Physics · Physics 2020-10-20 Ehtibar Dzhafarov

We consider sequential hypothesis testing between two quantum states using adaptive and non-adaptive strategies. In this setting, samples of an unknown state are requested sequentially and a decision to either continue or to accept one of…

Quantum Physics · Physics 2023-03-07 Yonglong Li , Vincent Y. F. Tan , Marco Tomamichel

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…

Contextuality is regarded as a non-classical feature, challenging our everyday intuition; quantum contextuality is currently seen as a resource for many applications in quantum computation, being responsible for quantum advantage over…

Quantum Physics · Physics 2020-12-16 Roberto D. Baldijao , Marcelo Terra Cunha

Contextuality is a central property in comparative analysis of classical, quantum, and supercorrelated systems. We examine and compare two well-motivated approaches to contextuality. One approach ("contextuality-by-default") is based on the…

Quantum Physics · Physics 2016-01-21 J. Acacio de Barros , Ehtibar N. Dzhafarov , Janne V. Kujala , Gary Oas

A common experimental strategy for demonstrating non-classical correlations is to show violation of a Bell inequality by measuring a continuously emitted stream of entangled photon pairs. The measurements involve the detection of photons by…

Quantum Physics · Physics 2015-03-11 Emanuel Knill , Scott Glancy , Sae Woo Nam , Kevin Coakley , Yanbao Zhang

One of the basic lessons of quantum theory is that one cannot obtain information on an unknown quantum state without disturbing it. Hence, by performing a certain measurement, we limit the other possible measurements that can be effectively…

Quantum Physics · Physics 2018-08-24 Erkka Haapasalo , Teiko Heinosaari , Takayuki Miyadera

In this work, we deal with the relaxation of two central assumptions in standard locally realistic hidden variable (LRHV) inequalities: free will in choosing measurement settings, and the presence of perfect detectors at the measurement…

Quantum Physics · Physics 2023-02-07 Abhishek Sadhu , Siddhartha Das

Quantum coherence is one of the clearest departures from classical physics, exhibited when a system is in a superposition of different basis states. Here the coherent superposition of three motional Fock states of a single trapped ion is…

Many seemingly paradoxical effects are known in the predictions for outcomes of intermediate measurements made on pre- and post-selected quantum systems. Despite appearances, these effects do not demonstrate the impossibility of a…

Quantum Physics · Physics 2007-05-23 M. S. Leifer , R. W. Spekkens

We show that contextual hidden variables including the effect of the measuring devices can be backward-propagated by means of the Green's function to initial Cauchy hidden data. If this data is uncorrelated in spacelike-disjoint sets, the…

Quantum Physics · Physics 2023-08-01 Álvaro García López

Quantum measurements are noncontextual, with outcomes independent of which other commuting observables are measured at the same time, when consistently analyzed using principles of Hilbert space quantum mechanics rather than classical…

Quantum Physics · Physics 2013-06-06 Robert B. Griffiths

We introduce a new information-theoretic formulation of quantum measurement uncertainty relations, based on the notion of relative entropy between measurement probabilities. In the case of a finite-dimensional system and for any approximate…

Mathematical Physics · Physics 2018-03-02 Alberto Barchielli , Matteo Gregoratti , Alessandro Toigo