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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

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

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

Weak measurement has provided new insight into the nature of quantum measurement, by demonstrating the ability to extract average state information without fully projecting the system. For single qubit measurements, this partial projection…

We report an unusual buildup of the quantum coherence in a qubit subjected to non-Hermitian evolution generated by a Parity-Time ($\mathcal{PT}$) symmetric Hamiltonian, which is reinterpreted as a Hermitian system in a higher dimensional…

Quantum Physics · Physics 2021-06-14 Javid Naikoo , Swati Kumari , A. K. Pan , Subhashish Banerjee

We study the decay process in an open system, emphasizing on the relevance of the environment's spectral structure. Non-Markovian effects are included to quantitatively analyze the degradation rate of the coherent evolution. The way in…

Quantum Physics · Physics 2011-11-01 Axel D. Dente , Pablo R. Zangara , Horacio M. Pastawski

The relation between genuine multipartite entanglement in the pure state of a collection of N qubits and the nonclassical correlations in its two-qubit subsystems is studied. Quantum discord is used as the quantifier of nonclassical…

Quantum Physics · Physics 2022-08-31 Chandan Mahto , Vijay Pathak , Ardra K. S. , Anil Shaji

We study Leggett-Garg inequalities (LGIs) for a two level system (TLS) undergoing Markovian dynamics described by unital maps. We find analytic expression of LG parameter $K_{3}$ (simplest variant of LGIs) in terms of the parameters of two…

Quantum Physics · Physics 2023-04-25 Sayan Ghosh , Anant V. Varma , Sourin Das

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

Macrorealism formalizes the intuitive notion that at any given time the system occupies a definite state and that the evolution of the system is independent of the measurements performed on it, in contrast to the principles of quantum…

We determine the total state dynamics of a dephasing open quantum system using the standard environment of harmonic oscillators. Of particular interest are random unitary approaches to the same reduced dynamics and system-environment…

Quantum Physics · Physics 2015-06-04 Ansgar Pernice , Julius Helm , Walter T. Strunz

The Leggett-Garg (LG) inequalities were introduced, as a temporal parallel of the Bell inequalities, to test macroscopic realism -- the view that a macroscopic system evolving in time possesses definite properties which can be determined…

Quantum Physics · Physics 2020-01-08 J. J. Halliwell

We report on a stringent test of the non-classicality of the motion of a massive quantum particle, which propagates on a discrete lattice. Measuring temporal correlations of the position of single atoms performing a quantum walk, we observe…

Quantum Physics · Physics 2015-02-11 Carsten Robens , Wolfgang Alt , Dieter Meschede , Clive Emary , Andrea Alberti

Based on the experimental evidence that impurities contribute to the dissipation properties of solid-state open quantum systems, we provide here a description in terms of nonlinear quantum Langevin equations of the role played by two-level…

Quantum Physics · Physics 2017-12-27 Juuso Manninen , Souvik Agasti , Francesco Massel

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

We study the non-Markovianity of the dynamics of open quantum systems focusing on the cases of independent and common environmental interactions. We investigate the degree of non-Markovianity quantified by two distinct measures proposed by…

Quantum Physics · Physics 2013-08-22 Felipe F. Fanchini , Goktug Karpat , Leonardo K. Castelano , Daniel Z. Rossatto

We explore the relationship between Kochen-Specker quantum contextuality and Bell-nonclassicality for ensembles of two-qubit pure states. We present a comparative analysis showing that the violation of a noncontextuality inequality on a…

Quantum Physics · Physics 2024-02-26 Giovanni Scala , Antonio Mandarino

We study dynamics of nonclassical correlations by exactly solving a model consisting of two atomic qubits with spontaneous emission. We find that the nonclassical correlations defined by different measures give different qualitative…

Quantum Physics · Physics 2012-02-01 Ming-Liang Hu , Heng Fan

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

The connection between the Leggett-Garg inequality and optimal scenarios from the point of view of quantum metrology is investigated for perfect and noisy general dichotomic measurements. In this context, we show that the Fisher information…