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We introduce a set of Bell inequalities for a three-qubit system. Each inequality within this set is violated by all generalized GHZ states. More entangled a generalized GHZ state is, more will be the violation. This establishes a relation…

Quantum Physics · Physics 2017-11-02 Arpan Das , Chandan Datta , Pankaj Agrawal

Quantum mechanics predicts that measurements of incompatible observables carry a minimum uncertainty which is independent of technical deficiencies of the measurement apparatus or incomplete knowledge of the state of the system. Nothing yet…

Quantum Physics · Physics 2013-06-14 Davide Girolami , Tommaso Tufarelli , Gerardo Adesso

Measurements with randomly chosen settings determine many important properties of quantum states without the need for a shared reference frame or calibration. They naturally emerge in the context of quantum communication and quantum…

We show that there are Bell-type inequalities for noncontextual theories that are violated by any quantum state. One of these inequalities between the correlations of compatible measurements is particularly suitable for testing this…

Quantum Physics · Physics 2009-07-28 Adan Cabello

Quantum theory predicts and experiments confirm that nature can produce correlations between distant events that are nonlocal in the sense of violating a Bell inequality. Nevertheless, Bell's strong sentence {\it Correlations cry out for…

Bell's test, initially devised to distinguish quantum theory from local hidden variable models through {violations of local bounds}, is also a common tool for detecting entanglement. For this purpose, one can assume the quantum description…

Quantum Physics · Physics 2026-04-21 Liang-Liang Sun , Yong-Shun Song , Sixia Yu

It has been suggested that there may exist quantum correlations that go beyond entanglement. The existence of such correlations can be revealed by quantum discord, but not by the conventional measure of entanglement. We argue that a state…

Quantum Physics · Physics 2016-09-30 Pankaj Agrawal , Sk Sazim , Indranil Chakrabarty , Arun K. Pati

Bell's theorem is typically understood as the proof that quantum theory is incompatible with local-hidden-variable models. More generally, we can see the violation of a Bell inequality as witnessing the impossibility of explaining quantum…

Bell nonlocality is a fundamental phenomenon of quantum physics as well as an essential resource for various tasks in quantum information processing. It is known that for the observation of nonlocality the measurements on a quantum system…

Quantum Physics · Physics 2025-07-16 Martin Plávala , Otfried Gühne , Marco Túlio Quintino

Bell inequalities have traditionally been used to demonstrate that quantum theory is nonlocal, in the sense that there exist correlations generated from composite quantum states that cannot be explained by means of local hidden variables.…

Violations of Bell inequalities in classical optics have been demonstrated in terms of field mean intensities and correlations, however, the quantum meaning of violations point to statistics and probabilities. We present a violation of Bell…

Quantum Physics · Physics 2023-01-31 Laura Ares , Alfredo Luis

Violation of local realism via Bell inequality - a profound and counterintuitive manifestation of quantum theory that conflicts with the prediction of local realism - is viewed to be intimately linked with quantum entanglement. Experimental…

This paper provides a systematic analysis of Bell experiments from the relational perspective, demonstrating that the apparent ``nonlocality'' of quantum mechanics stems from a problematic application of relativistic principles rather than…

Quantum Physics · Physics 2025-09-11 Jan van Neerven , Marijn Waaijer

We show that bipartite entanglements involving non-orthogonal states are {\it necessarily nonmaximally} entangled, however {\it small} the non-orthogonality may be. How the deviation from maximal entanglement is related to nonorthogonality…

Quantum Physics · Physics 2007-05-23 Dipankar Home , M K Samal

We derive a set of Bell-type inequalities for arbitrarily high-dimensional systems, based on the assumption of partial separability in the hybrid local-nonlocal hidden variable model. Partially entangled states would not violate the…

Quantum Physics · Physics 2015-05-20 Jing-Ling Chen , Dong-Ling Deng , Hong-Yi Su , Chunfeng Wu , C. H. Oh

It is well known that the effect of quantum nonlocality, as witnessed by violation of a Bell inequality, can be observed even when relaxing the assumption of measurement independence, i.e. allowing for the source to be partially correlated…

Quantum Physics · Physics 2023-11-17 Ivan Šupić , Jean-Daniel Bancal , Nicolas Brunner

Bell inequality is a mathematical inequality derived using the assumptions of locality and realism. Its violation guarantees the existence of quantum correlations in a quantum state. Bell inequality acts as an entanglement witness in the…

Quantum Physics · Physics 2016-07-29 Kaifeng Bu , Asutosh Kumar , Junde Wu

The discrepancy between maximally entangled states and maximally non-classical quantum correlations is well-known but still not well understood. We aim to investigate the relation between quantum correlations and entanglement in a family…

Quantum Physics · Physics 2016-03-01 Armin Tavakoli , Stefan Zohren , Marcin Pawlowski

We consider general settings of Bell inequality experiments with many parties, where each party chooses from a finite number of measurement settings each with a finite number of outcomes. We investigate the constraints that Bell…

Quantum Physics · Physics 2015-03-19 Matty J. Hoban , Joel J. Wallman , Dan E. Browne

Proposals for Bell inequality tests on systems restricted by superselection rules often require operations that are difficult to implement in practice. In this paper, we derive a new Bell inequality, where pairs of states are used to…

Quantum Physics · Physics 2015-05-19 Libby Heaney , Seung-Woo Lee , Dieter Jaksch