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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

Leggett Garg inequalities (LGIs) test the incompatibility between the notion of macrorealism and quantum mechanics. For unitary dynamics, the optimal quantum violation of an LGI is constrained by the L\"uders bound. However, the LGIs does…

Quantum Physics · Physics 2022-05-18 Asmita Kumari , A. K. Pan

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

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 (LGI) places a bound for the distinction between quantum systems and classical systems. Despite that the tests of temporal quantum correlations on LGIs have been studied in Hermitian realm, there are still…

Quantum Physics · Physics 2024-06-21 Pengfei Lu , Xinxin Rao , Teng Liu , Yang Liu , Ji Bian , Feng Zhu , Le Luo

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

We investigate the three-term Leggett-Garg inequality (LGI) for a two-level quantum system undergoing parity-time (PT ) symmetric dynamics governed by a non-Hermitian Hamiltonian, when a sequence of dichotomic projective measurements are…

Quantum Physics · Physics 2021-03-24 H. S. Karthik , Akshata Shenoy Hejamadi , A. R. Usha Devi

Leggett-Garg inequalities are tests of macroscopic realism that can be violated by quantum mechanics. In this letter, we realise photonic Leggett-Garg tests on a three-level system and implement measurements that admit three distinct…

Quantum Physics · Physics 2018-02-05 Kunkun Wang , Clive Emary , Xiang Zhan , Zhihao Bian , Jian Li , Peng Xue

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

We report on an experiment that demonstrates the violation of a Leggett-Garg inequality (LGI) with neutrons. LGIs have been proposed in order to assess how far the predictions of quantum mechanics defy macroscopic realism. With LGIs,…

Quantum Physics · Physics 2024-07-08 Elisabeth Kreuzgruber , Richard Wagner , Niels Geerits , Hartmut Lemmel , Stephan Sponar

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

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

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

This study investigates the emergence of macroscopic classical behavior from quantum foundations via the entropic Leggett--Garg inequality. We introduce a geometric framework for deriving entropic Leggett--Garg inequalities with…

Quantum Physics · Physics 2025-12-01 Qi-Hong Cai , Xue-Hao Yu , Ma-Cheng Yang , Ao-Xiang Liu , Cong-Feng Qiao

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

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

I study several aspects of tests of macrorealism (MR), which for a given data set serves to give a quantitative signal of the presence of a specific notion of non-classical behaviour. The insufficiency of classical understanding underpins…

Quantum Physics · Physics 2024-02-27 Clement Mawby

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 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 discuss the use of inequalities of the Leggett-Garg type (LGtI) to witness quantum coherence and present the first experimental violation of this type of inequalities using a light-matter interfaced system. By separately benchmarking the…

Quantum Physics · Physics 2015-09-11 Zong-Quan Zhou , Susana F. Huelga , Chuan-Feng Li , Guang-Can Guo
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