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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 propose a test of macrorealism that exploits the contextuality of two-time correlation functions to escape the so-called "clumsiness loophole" that plagues Leggett-Garg inequalities. The non-contextuality of reduced joint probability…

Quantum Physics · Physics 2023-11-15 Devashish Pandey , Xavier Oriols , Guillermo Albareda

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 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

Temporal steering and violation of the Leggett-Garg inequality are two different ways of probing the violation of macro-realistic assumptions in quantum mechanics. It is shown here that under unitary evolution and projective measurements…

Quantum Physics · Physics 2016-11-18 Shiladitya Mal , Archan S. Majumdar , Dipankar Home

We interpret the Leggett-Garg (LG) inequality as a kind of contextual probabilistic inequality in which one combines data collected in experiments performed for three different contexts. In the original version of the inequality these…

Neurons and Cognition · Quantitative Biology 2015-06-18 Masanari Asano , Takahisa Hashimoto , Andrei Khrennikov , Masanori Ohya , Yoshiharu Tanaka

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

The Leggett-Garg inequality is a widely used test of the "quantumness" of a system, and involves correlations between measurements realized at different times. According to its widespread interpretation, a violation of the Legget-Garg…

Quantum Physics · Physics 2016-01-07 Saulo V. Moreira , Arne Keller , Thomas Coudreau , Perola Milman

Contextuality is a central property in comparative analysis of classical, quantum, and supercorrelated systems. We examine and compare two well-motivated approaches to contextuality. One approach ("contextuality-by-default") is based on the…

Quantum Physics · Physics 2016-01-21 J. Acacio de Barros , Ehtibar N. Dzhafarov , Janne V. Kujala , Gary Oas

Leggett-Garg inequalities are an important milestone in our quest to bridge the classical-quantum divide. An experimental investigation of these inequalities requires the so called \emph{non-invasive measurements}(NIM). It has become…

Quantum Physics · Physics 2015-09-18 N. D. Hari Dass

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

In contrast to the spatial Bell's inequalities, which probe entanglement between spatially-separated systems, the Leggett-Garg inequalities test the correlations of a single system measured at different times. Violation of a genuine…

Quantum Physics · Physics 2014-01-31 Clive Emary , Neill Lambert , Franco Nori

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

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

We consider temporal correlations of particles with arbitrary spin. We show that the Leggett-Garg inequality can be maximally violated irrespective of the value of spin, thus improving upon an earlier result by Kofler and Brukner [Phys.…

Quantum Physics · Physics 2016-06-22 Shiladitya Mal , A. S Majumdar

We consider two different types of conditions which were proposed to test macrorealism in the context of a system described by a single dichotomic variable Q. This is the view that a macroscopic system evolving in time possesses definite…

Quantum Physics · Physics 2017-07-26 J. J. Halliwell

We report an experimental study of recently formulated entropic Leggett-Garg inequality (ELGI) by Usha Devi et al. (arXiv: 1208.4491v2 (2012)). This inequality places a bound on the statistical measurement outcomes of dynamical observables…

Quantum Physics · Physics 2013-05-08 Hemant Katiyar , Abhishek Shukla , Rama Koteswara Rao , T. S. Mahesh

Random number generators play an essential role in cryptography and key distribution. It is thus important to verify whether the random numbers generated from these devices are genuine and unpredictable by any adversary. Recently, quantum…

Quantum Physics · Physics 2025-01-07 Shubhayan Sarkar

The Leggett-Garg inequality (LGI) as a temporal analogue of Bell's inequality, derived using the notion of realism, is applied in a hitherto unexplored context involving the weak interaction induced two-state oscillations of decaying…

Quantum Physics · Physics 2015-06-15 D. Gangopadhyay , D. Home , A. Sinha Roy

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