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The usual formulation of Macrorealism is recast to make this notion fully concurrent with the basic ideas behind classical physics. The assumption of non-invasiveness of measurements is dropped. Instead, it is assumed that the current state…

Quantum Physics · Physics 2010-09-10 Marek Zukowski

In this paper we focus on the underlying quantum structure of temporal correlations and show their peculiar nature which differentiate them from spatial quantum correlations. We show rigorously that a particular entangled history, which can…

Quantum Physics · Physics 2020-11-18 Marcin Nowakowski

We derive a set of Leggett-Garg inequalities (temporal Bell's inequalities) for the moment generating function of charge transferred through a conductor. Violation of these inequalities demonstrates the absence of a macroscopic-real…

Mesoscale and Nanoscale Physics · Physics 2012-09-10 Clive Emary

The Leggett-Garg inequality (LGI), derived under the assumption of realism, acts as the temporal Bell's inequality. It is studied in electromagnetic and strong interaction like photonics, superconducting qu-bits and nuclear spin. Until the…

High Energy Physics - Phenomenology · Physics 2017-11-16 Qiang Fu , Xurong Chen

Investigation the boundary between quantum mechanical description and classical realistic view is of fundamental importance. The Leggett-Garg inequality provides a criterion to distinguish between quantum systems and classical systems, and…

Quantum Physics · Physics 2022-05-04 Maimaitiyiming Tusun , Wei Cheng , Zihua Chai , Yang Wu , Ya Wang , Xing Rong , Jiangfeng Du

Leggett-Garg inequality (LGI) studies the temporal correlation in the evolution of physical systems. Classical systems obey the LGI but quantum systems may violate it. The extent of the violation depends on the dimension of the quantum…

The Leggett-Garg (LG) inequalities were proposed in order to assess whether sets of pairs of sequential measurements on a single quantum system can be consistent with an underlying notion of macrorealism. Here, the LG inequalities are…

Quantum Physics · Physics 2016-03-02 J. J. Halliwell

In the tests for macrorealism proposed by Leggett and Garg, the temporal correlation functions of a dichotomic variable Q must be measured in a non-invasive way to rule out alternative classical explanations of Leggett-Garg inequality…

Quantum Physics · Physics 2019-02-27 J. J. Halliwell

The rise of quantum information theory has lent new relevance to experimental tests for non-classicality, particularly in controversial cases such as adiabatic quantum computing superconducting circuits. The Leggett-Garg inequality is a…

Quantum Physics · Physics 2015-03-13 Mark M. Wilde , Ari Mizel

The Leggett-Garg inequalities probe the classical-quantum boundary by putting limits on the sum of pairwise correlation functions between classical measurement devices that consecutively measured the same quantum system. The apparent…

Quantum Physics · Physics 2019-09-13 Christoph Adami

In this paper we provide an experimental illustration of Page and Wootters' quantum time mechanism that is able to describe two-time quantum correlation functions. This allows us to test a Leggett-Garg inequality, showing a violation from…

Quantum Physics · Physics 2017-11-22 Ekaterina Moreva , Marco Gramegna , Giorgio Brida , Lorenzo Maccone , Marco Genovese

We formulate entropic Leggett-Garg inequalities, which place constraints on the statistical outcomes of temporal correlations of observables. The information theoretic inequalities are satisfied if macrorealism holds. We show that the…

Quantum Physics · Physics 2013-05-21 A. R. Usha Devi , H. S. Karthik , Sudha , A. K. Rajagopal

In a recent paper, Chatterjee et al. [Phys. Rev. Lett 135, 220202 (2025)] analyze and experimentally implement a specific unitary evolution of a simple quantum system. The authors refer to this type of dynamics as a "superposition of…

Quantum Physics · Physics 2026-01-27 Antoni Wójcik , Jan Wójcik

Despite the great success of quantum mechanics, questions regarding its application still exist and the boundary between quantum and classical mechanics remains unclear. Based on the philosophical assumptions of macrorealism and noninvasive…

Quantum Physics · Physics 2012-04-24 Jin-Shi Xu , Chuan-Feng Li , Xu-Bo Zou , Guang-Can Guo

We generalize the derivation of Leggett-Garg inequalities to systematically treat a larger class of experimental situations by allowing multi-particle correlations, invasive detection, and ambiguous detector results. Furthermore, we show…

Quantum Physics · Physics 2015-03-18 J. Dressel , C. J. Broadbent , J. C. Howell , A. N. Jordan

In this paper we propose a time-independent \textit{equality} and time-dependent \textit{inequality}, suitable for an experimental test of the hypothesis of realism. The derivation of these relations is based on the concept of conditional…

Quantum Physics · Physics 2017-05-10 N. Nikitin , K. Toms

The possibility of observing violations of temporal Bell inequalities, originally proposed by Leggett as a mean of testing the quantum mechanical delocalization of suitably chosen macroscopic bodies, is discussed by taking into account the…

Quantum Physics · Physics 2009-10-31 Tommaso Calarco , Marcello Cini , Roberto Onofrio

Quantum theory predicts and experiments confirm that nature can produce correlations between distant events that are nonlocal in the sense of violating a Bell inequality. Nevertheless, Bell's strong sentence {\it Correlations cry out for…

In conventional NMR experiments, the Zeeman energy gaps of the nuclear spin ensembles are much lower than their thermal energies, and accordingly exhibit tiny polarizations. Generally such low-purity quantum states are devoid of quantum…

Quantum Physics · Physics 2017-08-08 T. S. Mahesh , C. S. Sudheer Kumar , Udaysinh T. Bhosale

The Leggett-Garg inequality (LGI) is a temporal analogue of Bell's inequality and provides a quantitative test of the nonclassicality of a system through its violation. We analytically investigate the violation of the LGI in the context of…

General Relativity and Quantum Cosmology · Physics 2026-01-29 Kimihiro Nomura , Akira Taniguchi , Kazushige Ueda