scholarly journals The problem of quantum correlations and the totalitarian principle

2019 ◽  
Vol 377 (2157) ◽  
pp. 20190136 ◽  
Author(s):  
Adán Cabello
Keyword(s):  
Quantum Mechanics ◽  
Quantum Correlations ◽  
Short Version ◽  
Theme Issue ◽  
Independent Realization

The totalitarian principle establishes that ‘anything not forbidden is compulsory’. The problem of quantum correlations is explaining what selects the set of quantum correlations for a Bell and Kochen–Specker (KS) contextuality scenario. Here, we show that two assumptions and a version of the totalitarian principle lead to the quantum correlations. The assumptions are that there is a non-empty set of correlations for any KS contextuality scenario and a statistically independent realization of any two KS experiments. The version of the totalitarian principle says that any correlation not forbidden by these assumptions can be produced. This paper contains a short version of the proof (presented elsewhere) and explores some implications of the result. This article is part of the theme issue ‘Contextuality and probability in quantum mechanics and beyond’.

scholarly journals Quantum Mechanics and Global Determinism

Quanta ◽  
2018 ◽  
Vol 7 (1) ◽  
pp. 40 ◽  
Author(s):  
Emily Christine Adlam
Keyword(s):  
Quantum Mechanics ◽  
Quantum Correlations ◽  
Deterministic Theory ◽  
No Signaling ◽  
Open Question ◽  
Global Determinism

It is proposed that certain features of quantum mechanics may be perspectival effects, which arise because experiments performed on locally accessible variables can only uncover a certain subset of the correlations exhibited by an underlying deterministic theory. This hypothesis is used to derive the no-signaling principle, thus resolving an open question regarding the apparently fine-tuned nature of quantum correlations. Some potential objections to this approach are then discussed and answered.Quanta 2018; 7: 40–53.

scholarly journals Relating causal and probabilistic approaches to contextuality

2019 ◽  
Vol 377 (2157) ◽  
pp. 20190133
Author(s):  
Matt Jones
Keyword(s):  
Quantum Mechanics ◽  
Causal Model ◽  
Probability Distributions ◽  
Hidden Variables ◽  
Measurement Model ◽  
Direct Influence ◽  
Theme Issue ◽  
Full System ◽  
General Systems ◽  
New Interpretation

A primary goal in recent research on contextuality has been to extend this concept to cases of inconsistent connectedness, where observables have different distributions in different contexts. This article proposes a solution within the framework of probabi- listic causal models, which extend hidden-variables theories, and then demonstrates an equivalence to the contextuality-by-default (CbD) framework. CbD distinguishes contextuality from direct influences of context on observables, defining the latter purely in terms of probability distributions. Here, we take a causal view of direct influences, defining direct influence within any causal model as the probability of all latent states of the system in which a change of context changes the outcome of a measurement. Model-based contextuality (M-contextuality) is then defined as the necessity of stronger direct influences to model a full system than when considered individually. For consistently connected systems, M-contextuality agrees with standard contextuality. For general systems, it is proved that M-contextuality is equivalent to the property that any model of a system must contain ‘hidden influences’, meaning direct influences that go in opposite directions for different latent states, or equivalently signalling between observers that carries no information. This criterion can be taken as formalizing the ‘no-conspiracy’ principle that has been proposed in connection with CbD. M-contextuality is then proved to be equivalent to CbD-contextuality, thus providing a new interpretation of CbD-contextuality as the non-existence of a model for a system without hidden direct influences. This article is part of the theme issue ‘Contextuality and probability in quantum mechanics and beyond’.

scholarly journals Indistinguishability and the origins of contextuality in physics

2019 ◽  
Vol 377 (2157) ◽  
pp. 20190150 ◽  
Author(s):  
J. Acacio de Barros ◽  
Federico Holik ◽  
Décio Krause
Keyword(s):  
Quantum Mechanics ◽  
Set Theory ◽  
Physical Quantity ◽  
Theoretical Framework ◽  
Quantum Systems ◽  
Strong Sense ◽  
Theme Issue ◽  
Identity Of Indiscernibles ◽  
Theoretical Structure

In this work, we discuss a formal way of dealing with the properties of contextual systems. Our approach is to assume that properties describing the same physical quantity, but belonging to different measurement contexts, are indistinguishable in a strong sense. To construct the formal theoretical structure, we develop a description using quasi-set theory, which is a set-theoretical framework built to describe collections of elements that violate Leibnitz's principle of identity of indiscernibles. This framework allows us to consider a new ontology in order to study the properties of quantum systems. This article is part of the theme issue ‘Contextuality and probability in quantum mechanics and beyond’.

scholarly journals Reality, Indeterminacy, Probability, and Information in Quantum Theory

Entropy ◽  
2020 ◽  
Vol 22 (7) ◽  
pp. 747
Author(s):  
Arkady Plotnitsky
Keyword(s):  
Information Theory ◽  
Quantum Mechanics ◽  
Quantum Theory ◽  
Quantum Information ◽  
Quantum Correlations ◽  
Quantum Information Theory ◽  
Quantum Phenomena

Following the view of several leading quantum-information theorists, this paper argues that quantum phenomena, including those exhibiting quantum correlations (one of their most enigmatic features), and quantum mechanics may be best understood in quantum-informational terms. It also argues that this understanding is implicit already in the work of some among the founding figures of quantum mechanics, in particular W. Heisenberg and N. Bohr, half a century before quantum information theory emerged and confirmed, and gave a deeper meaning to, to their insights. These insights, I further argue, still help this understanding, which is the main reason for considering them here. My argument is grounded in a particular interpretation of quantum phenomena and quantum mechanics, in part arising from these insights as well. This interpretation is based on the concept of reality without realism, RWR (which places the reality considered beyond representation or even conception), introduced by this author previously, in turn, following Heisenberg and Bohr, and in response to quantum information theory.

scholarly journals Proposal to Test a Transient Deviation from Quantum Mechanics’ Predictions for Bell’s Experiment

Entropy ◽  
2021 ◽  
Vol 23 (12) ◽  
pp. 1589
Author(s):  
Alejandro Andrés Hnilo ◽  
Monica Beatriz Agüero ◽  
Marcelo Gregorio Kovalsky
Keyword(s):  
Quantum Mechanics ◽  
Hidden Variables ◽  
Quantum Correlations ◽  
Entangled State ◽  
Particle Detection ◽  
Specific Test ◽  
Nonlinear Operators ◽  
Model Following ◽  
Proposed Model ◽  
Faster Than Light

Quantum mechanics predicts correlations between measurements performed in distant regions of a spatially spread entangled state to be higher than allowed by intuitive concepts of Locality and Realism. These high correlations forbid the use of nonlinear operators of evolution (which would be desirable for several reasons), for they may allow faster-than-light signaling. As a way out of this situation, it has been hypothesized that the high quantum correlations develop only after a time longer than L/c has elapsed (where L is the spread of the entangled state and c is the velocity of light). In shorter times, correlations compatible with Locality and Realism would be observed instead. A simple hidden variables model following this hypothesis is described. It is based on a modified Wheeler–Feynman theory of radiation. This hypothesis has not been disproved by any of the experiments performed to date. A test achievable with accessible means is proposed and described. It involves a pulsed source of entangled states and stroboscopic record of particle detection during the pulses. Data recorded in similar but incomplete optical experiments are analyzed, and found consistent with the proposed model. However, it is not claimed, in any sense, that the hypothesis has been validated. On the contrary, it is stressed that a complete, specific test is absolutely needed.

scholarly journals Causation does not explain contextuality

Quantum ◽  
2018 ◽  
Vol 2 ◽  
pp. 63 ◽  
Author(s):  
Sally Shrapnel ◽  
Fabio Costa
Keyword(s):  
Quantum Mechanics ◽  
Causal Structure ◽  
Quantum Correlations ◽  
Global Constraints ◽  
Local Constraints ◽  
The Past ◽  
Interpretations Of Quantum Mechanics ◽  
The World ◽  
Non Local ◽  
Initial States

Realist interpretations of quantum mechanics presuppose the existence of elements of reality that are independent of the actions used to reveal them. Such a view is challenged by several no-go theorems that show quantum correlations cannot be explained by non-contextual ontological models, where physical properties are assumed to exist prior to and independently of the act of measurement. However, all such contextuality proofs assume a traditional notion of causal structure, where causal influence flows from past to future according to ordinary dynamical laws. This leaves open the question of whether the apparent contextuality of quantum mechanics is simply the signature of some exotic causal structure, where the future might affect the past or distant systems might get correlated due to non-local constraints. Here we show that quantum predictions require a deeper form of contextuality: even allowing for arbitrary causal structure, no model can explain quantum correlations from non-contextual ontological properties of the world, be they initial states, dynamical laws, or global constraints.

scholarly journals Hilbert space multidimensional modelling of continuous measurements

2019 ◽  
Vol 377 (2157) ◽  
pp. 20190142
Author(s):  
J. R. Busemeyer ◽  
Z. Wang
Keyword(s):  
Hilbert Space ◽  
Quantum Mechanics ◽  
Data Fusion ◽  
State Vector ◽  
Joint Distribution ◽  
Context Effect ◽  
Theme Issue ◽  
Multiple Contexts ◽  
Complete Set ◽  
Multidimensional Modelling

Data fusion problems arise when a researcher needs to analyse results obtained by measuring empirical variables under different measurement contexts. A context is defined by a subset of variables taken from a complete set of variables under investigation. Multiple contexts can be formed from different subsets, which produce a separate distribution of measurements associated with each context. A context effect occurs when the distributions produced by the different contexts cannot be reproduced by marginalizing over a complete joint distribution formed by all the variables. We propose a Hilbert space multidimensional theory that uses a state vector and measurement operators to account for multiple distributions produced by different contexts. This article is part of the theme issue ‘Contextuality and probability in quantum mechanics and beyond’.

scholarly journals Relativistic independence bounds nonlocality

2019 ◽  
Vol 5 (4) ◽  
pp. eaav8370 ◽  
Author(s):  
Avishy Carmi ◽  
Eliahu Cohen
Keyword(s):  
Quantum Mechanics ◽  
Quantum Correlations ◽  
Physical Principle ◽  
Quantum Nonlocality ◽  
Measuring Instruments ◽  
Uncertainty Relations ◽  
The Past ◽  
Nonlocal Correlations

If nature allowed nonlocal correlations other than those predicted by quantum mechanics, would that contradict some physical principle? Various approaches have been put forward in the past two decades in an attempt to single out quantum nonlocality. However, none of them can explain the set of quantum correlations arising in the simplest scenarios. Here, it is shown that generalized uncertainty relations, as well as a specific notion of locality, give rise to both familiar and new characterizations of quantum correlations. In particular, we identify a condition, relativistic independence, which states that uncertainty relations are local in the sense that they cannot be influenced by other experimenters’ choices of measuring instruments. We prove that theories with nonlocal correlations stronger than the quantum ones do not satisfy this notion of locality, and therefore, they either violate the underlying generalized uncertainty relations or allow experimenters to nonlocally tamper with the uncertainty relations of their peers.

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