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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

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

It remains an open question how realist view of macroscopic world emerges from quantum formalism. For testing the macrorealism in quantum domain, an interesting approach was put forward by Leggett and Garg in $1985$, by formulating a…

Quantum Physics · Physics 2017-08-16 Swati Kumari , A. K. Pan

The quantum description of the microscopic world is incompatible with the classical description of the macroscopic world, both mathematically and conceptually. Nevertheless, it is generally accepted that classical mechanics emerges from…

Quantum Physics · Physics 2025-08-11 Miguel Gallego , Borivoje Dakić

In this study, we determine a violation of the Leggett-Garg inequalities due to gravitational interaction in a hybrid system consisting of a harmonic oscillator and a spatially localized superposed particle. The violation of the…

Quantum Physics · Physics 2022-08-23 Akira Matsumura , Yasusada Nambu , Kazuhiro Yamamoto

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

We consider maximal violations of the Leggett-Garg inequality, obtained by maximising over all possible measurement operators, in relation to non-unitary aspects of the system dynamics. We model the action of an environment on a qubit in…

Quantum Physics · Physics 2013-04-22 Clive Emary

The Leggett-Garg inequality, an analogue of Bell's inequality involving correlations of measurements on a system at different times, stands as one of the hallmark tests of quantum mechanics against classical predictions. The phenomenon of…

Quantum Physics · Physics 2016-07-29 J. A. Formaggio , D. I. Kaiser , M. M. Murskyj , T. E. Weiss

We investigate the violation of Leggett-Garg (LG) inequalities inquantum dots with the stationarity assumption. By comparing two types of LG inequalities, we find a better one which is easier to be tested in experiment. In addition, we show…

Quantum Physics · Physics 2015-05-30 Yong-Nan Sun , Yang Zou , Rong-Chun Ge , Jian-Shun Tang , Chuan-Feng Li , Guang-Can Guo

We prove that a violation of a Leggett-Garg inequality for bounded observables in stationary pure states and thermal states yields a rigorous lower bound on the quantum Fisher information. This turns a qualitative foundations test of…

Quantum Physics · Physics 2026-04-14 Nick Abboud , Yuntao Guan , Barry Bradlyn , Jorge Noronha

In two-party, two-input and two-output measurement scenario only relevant Bell's inequality is the Clauser-Horne-Shimony-Holt (CHSH) form. They also provide the necessary and sufficient conditions for local realism. Any other form, such as,…

Quantum Physics · Physics 2019-12-24 Swati Kumari , A. K. Pan

Macro-realistic description of systems is based majorly on two basic intuitions about the classical world, namely, macrorealism per se, that is, the system is always in a distinct state, and non-invasive measurements, that is, measurements…

Quantum Physics · Physics 2025-06-16 Shubhayan Sarkar

We study the fluctuations of the work performed on a driven quantum system, defined as the difference between subsequent measurements of energy eigenvalues. These work fluctuations are governed by statistical theorems with similar…

Quantum Physics · Physics 2017-07-19 Ralf Blattmann , Klaus Mølmer

We show how a test of macroscopic realism based on Leggett-Garg inequalities (LGIs) can be performed in a macroscopic system. Using a continuous-variable approach, we consider quantum non-demolition (QND) measurements applied to atomic…

We investigate the Leggett-Garg inequalities (LGIs) for a boson system whose observables are given by deforming the Pegg-Barnett phase operators. We consider two observables and show that the quantum Fourier transform is useful in the…

Quantum Physics · Physics 2023-02-09 Hiroo Azuma , William J. Munro , Kae Nemoto

Quantum theory contravenes classical macrorealism by allowing a system to be in a superposition of two or more physically distinct states, producing physical consequences radically different from that of classical physics. We show that a…

Quantum Physics · Physics 2026-02-03 Arijit Chatterjee , H. S. Karthik , T. S. Mahesh , A. R. Usha Devi

The Leggett-Garg (LG) test of macroscopic realism involves a series of dichotomic non-invasive measurements that are used to calculate a function which has a fixed upper bound for a macrorealistic system and a larger upper bound for a…

Quantum Physics · Physics 2017-02-23 Hemant Katiyar , Aharon Brodutch , Dawei Lu , Raymond Laflamme

In this paper we first analyse Leggett and Garg's argument to the effect that macroscopic realism contradicts quantum mechanics. After making explicit all the assumptions in Leggett and Garg's reasoning, we argue against the plausibility of…

Quantum Physics · Physics 2014-12-02 Guido Bacciagaluppi

Macroscopic realism (MR) is the notion that a time-evolving system possesses definite properties, irrespective of past or future measurements. Quantum mechanical theories can, however, produce violations of MR. Most research to date has…

Quantum Physics · Physics 2021-09-14 Shayan Majidy , Jonathan J. Halliwell , Raymond Laflamme

The Leggett-Garg inequality attempts to classify experimental outcomes as arising from one of two possible classes of physical theories: those described by macrorealism (which obey our intuition about how the macroscopic classical world…

Quantum Physics · Physics 2020-12-22 Huan-Yu Ku , Neill Lambert , Fong-Ruei Jhan , Clive Emary , Yueh-Nan Chen , Franco Nori