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Macrorealism is a classical world view asserting that the properties of macro-objects exist independently and irrespective of observation. One practical approach to test this view in quantum theory is to observe the quantum coherence for…

Quantum Physics · Physics 2020-12-29 A. K. Pan

Wigner's form of the local realist inequality is used to derive its temporal version for an oscillating two-level system involving two-time joint probabilities. Such an inequality may be regarded as a novel form of the Leggett-Garg…

Quantum Physics · Physics 2015-03-24 Debashis Saha , Shiladitya Mal , Prasanta K. Panigrahi , Dipankar Home

We show how to apply the Leggett-Garg inequality to opto-electro-mechanical systems near their quantum ground state. We find that by using a dichotomic quantum non-demolition measurement (via, e.g., an additional circuit-QED measurement…

Quantum Physics · Physics 2012-09-17 Neill Lambert , Robert Johansson , Franco Nori

Macroscopic realism is the thesis that macroscopically observable properties must always have definite values. The idea was introduced by Leggett and Garg (1985), who wished to show a conflict with the predictions of quantum theory.…

Quantum Physics · Physics 2018-02-02 R. Hermens , O. J. E. Maroney

We show violations of Leggett-Garg inequalities to be possible for single-mode cat-states evolving dynamically in the presence of a nonlinear quantum interaction arising from, for instance, a Kerr medium. In order to prove the results, we…

Quantum Physics · Physics 2019-04-03 Manushan Thenabadu , Margaret Reid

The Leggett-Garg inequalities have been proposed to identify the quantum behaviour of a system; specifically, the violation of macrorealism. They are usually implemented by performing two sequential measurements on quantum systems,…

Quantum Physics · Physics 2025-02-25 D. Melegari , M. Cardi , P. Solinas

Macroscopic realism (MR) is the view that a system may possess definite properties at any time independent of past or future measurements, and may be tested experimentally using the Leggett-Garg inequalities (LGIs). In this work we advance…

Macrorealism (MR) is the world view that certain quantities may take definite values at all times irrespective of past or future measurements and may be experimentally falsified via the Leggett-Garg (LG) inequalities. We put this world view…

Quantum Physics · Physics 2023-12-06 Clement Mawby , Jonathan Halliwell

Leggett-Garg inequalities (LGI) are constrains on certain combinations of temporal correlations obtained by measuring one and the same system at two different instants of time. The usual derivations of LGI assume \emph {macroscopic realism…

Quantum Physics · Physics 2014-06-24 Shiladitya Mal , Manik Banik , Sujit K Choudhary

We consider two necessary and sufficient conditions for macrorealism recently appeared in the literature, known as no-signaling-in-time and arrow-of-time conditions, respectively, and study them in the context of neutrino flavor…

High Energy Physics - Theory · Physics 2023-08-07 Massimo Blasone , Fabrizio Illuminati , Luciano Petruzziello , Kyrylo Simonov , Luca Smaldone

We realise a quantum three-level system with photons distributed among three different spatial and polarization modes. Ambiguous measurement of the state of the qutrit are realised by blocking one out for the three modes at any one time.…

Quantum Physics · Physics 2018-02-14 Kunkun Wang , Clive Emary , Mengyan Xu , Xiang Zhan , Zhihao Bian , Lei Xiao , Peng Xue

We construct quantifiable generalisations of Leggett-Garg tests for macro/ mesoscopic realism and noninvasive measurability that apply when not all outcomes of measurement can be identified as arising from one of two macroscopically…

Quantum Physics · Physics 2024-12-13 L. Rosales-Zárate , B. Opanchuk , Q. Y. He , M. D. Reid

Macroscopic Realism (MR) says that a macroscopic system is always determinately in one or other of the macroscopically distinguishable states available to it. The Leggett-Garg (LG) inequality was derived to allow experimental test of…

Quantum Physics · Physics 2014-12-22 Owen J. E Maroney , Christopher G Timpson

Contextuality means non-existence of a joint distribution for random variables recorded under mutually incompatible conditions, subject to certain constraints imposed on how the identity of these variables may change across these…

Quantum Physics · Physics 2015-02-06 Ehtibar N. Dzhafarov , Janne V. Kujala

A recent paper by Souza, Oliveira and Sarthour (SOS) reports the experimental violation of a Leggett-Garg inequality (sometimes referred to as a temporal Bell inequality). The inequality tests for quantum mechanical superposition: if the…

Quantum Physics · Physics 2012-07-13 George C. Knee , Erik M. Gauger , G. Andrew D. Briggs , Simon C. Benjamin

"Macrorealism" posits that a system possesses definite properties at all times and that we can discover these properties, in principle, without disturbing the system's subsequent behaviour. The Leggett-Garg inequalities are derived under…

Quantum Physics · Physics 2026-05-22 Arush Garg , Jonathan Halliwell , Taejas Venkataraman

The Leggett-Garg inequalities are a set of inequalities obeyed by classical systems but violated in quantum theory. Their violation has been taken as evidence that quantum theory lacks a `realistic' formulation. However in addition to…

Quantum Physics · Physics 2013-10-09 JM Yearsley

We investigate the relation between a refined version of Leggett and Garg conditions for macrorealism, namely the no-signaling-in-time (NSIT) conditions, and the quantum mechanical notion of nondisturbance between measurements. We show that…

Quantum Physics · Physics 2019-11-05 Roope Uola , Giuseppe Vitagliano , Costantino Budroni

As is well known, the macroscopic realism and the noninvasive measurability together lead to Leggett-Garg inequalities violated by quantum mechanics. We consider tests of the Leggett-Garg type with use of the $q$-entropies. For all…

Quantum Physics · Physics 2014-11-11 Alexey E. Rastegin

Macrorealism (MR) is the view that a system evolving in time possesses definite properties independent of past or future measurements and is traditionally tested for systems described at each time by a single dichotomic variable $Q$. A…

Quantum Physics · Physics 2020-07-15 J. J. Halliwell , C. Mawby