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Leggett Garg inequalities (LGIs) provide an elegant way for probing the incompatibility between the notion of macrorealism and quantum mechanics. For unitary dynamics, the optimal quantum violation of a LGI is constrained by the L\"uders…

Quantum Physics · Physics 2022-03-23 Asmita Kumari , A. K. Pan

According to the world view of macrorealism, the properties of a given system exist prior to and independent of measurement, which is incompatible with quantum mechanics. Leggett and Garg put forward a practical criterion capable of…

Quantum Physics · Physics 2018-06-27 Eugenio Roldán , Johannes Kofler , Carlos Navarrete-Benlloch

Standard Leggett and Garg inequalities (SLGIs) were formulated for testing the incompatibility between the classical worldview of macrorealism and quantum mechanics. In recent times, various other formulations, such as Wigner form of LGIs…

Quantum Physics · Physics 2017-10-17 Swati Kumari , A. K. Pan

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

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

In 1985, Leggett and Garg formulated a class of inequalities for testing the compatibility between macrorealism and quantum mechanics. In this paper, we point out that based on the same assumptions of macrorealism that are used in the…

Quantum Physics · Physics 2020-12-29 A. K. Pan , Md. Qutubuddin , Swati Kumari

"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 correlations between successive measurements of a quantum system can violate a family of Leggett-Garg Inequalities (LGIs) that are analogous to the violation of Bell's inequalities of measurements performed on spatially separated…

High Energy Physics - Phenomenology · Physics 2026-01-30 Kathrine Mørch Groth , Johann Ioannou-Nikolaides , D. Jason Koskinen , Markus Ahlers

In the Leggett-Garg approach to testing macrorealism, the two-time correlation functions, which are normally obtained by sequential measurements of a dichotomic variable Q, need to be measured in a non-invasive way in order to exclude…

Quantum Physics · Physics 2016-11-23 J. J. Halliwell

Macroscopic realism is a set of assumptions about how we experience the world at a classical level. While the Leggett-Garg inequalities are temporal correlations that are violated by quantum systems not obeying such macrorealism, the…

Quantum Physics · Physics 2025-12-23 Manish Ramchander , Arul Lakshminarayan

Leggett-Garg (LG) tests for macrorealism were originally designed to explore quantum coherence on the macroscopic scale. Interference experiments and systems modelled by harmonic oscillators provide useful examples of situations in which…

Quantum Physics · Physics 2021-03-31 J. J. Halliwell , A. Bhatnagar , E. Ireland , H. Nadeem , V. Wimalaweera

We propose a definition of determinism for a physical system that includes, besides the measured system, the measurement device and the surrounding environment. This enlarged system is assumed to follow a predefined trajectory starting from…

Quantum Physics · Physics 2013-09-17 Ramon Lapiedra , A. Perez

The search for empirical schemes to evidence the nonclassicality of large masses is a central quest of current research. However, practical schemes to witness the irreducible quantumness of an arbitrarily large mass are still lacking. To…

Quantum Physics · Physics 2024-01-17 Debarshi Das , Dipankar Home , Hendrik Ulbricht , Sougato Bose

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

Generalised dichotomic quantum measurements are fully characterised by two real parameters, dubbed as sharpness parameter and biasedness parameter. The trade-off between the degree of joint measurability, sharpness and biasedness of…

Quantum Physics · Physics 2020-03-17 Debarshi Das , Arindam Gayen , Ranit Das , Shiladitya Mal

In a recent Letter [PRL, 113, 050401 (2014)], it is shown that the quantum violation of a three-time Leggett-Garg inequality (LGI) for a dichotomic qutrit system can exceed the L$\ddot{u}$ders bound. This is obtained by using a degeneracy…

Quantum Physics · Physics 2018-11-07 Asmita Kumari , Md. Qutubuddin , 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

Leggett and Garg formulated macrorealist models encoding our intuition on classical systems, i.e., physical quantities have a definite value that can be measured with minimal disturbance, and with the goal of testing macroscopic quantum…

Quantum Physics · Physics 2024-02-26 Giuseppe Vitagliano , Costantino Budroni

The Leggett-Garg (LG) inequalities were introduced to test for the possible presence of macroscopic quantum coherence. Since such effects may be found in various types of macroscopic oscillators, we consider the application of the LG…

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

Macro-realism is the position that certain "macroscopic" observables must always possess definite values: e.g. the table is in some definite position, even if we don't know what that is precisely. The traditional understanding is that by…

Quantum Physics · Physics 2017-07-17 John-Mark A. Allen , Owen J. E. Maroney , Stefano Gogioso