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Bell inequality violations are often taken as evidence that quantum nonlocality guarantees intrinsic randomness, effectively playing the role of a "dice" at the heart of many device-independent cryptographic protocols. We show that there…

Quantum Physics · Physics 2025-09-11 Ravishankar Ramanathan , Yuan Liu , Stefano Pironio

Two approaches to extend Hardy's proof of nonlocality without inequalities to maximally entangled states of bipartite two-level systems are shown to fail. On one hand, it is shown that Wu and co-workers' proof [Phys. Rev. A 53, R1927…

Quantum Physics · Physics 2009-10-31 Adan Cabello

Bell theorems show how to experimentally falsify local realism. Conclusive falsification is highly desirable as it would provide support for the most profoundly counterintuitive feature of quantum theory - nonlocality. Despite the…

Quantum Physics · Physics 2012-02-22 Anne Broadbent , Hilary A. Carteret , Andre Allan Methot , Jonathan Walgate

We derive a bound on the precision of state estimation for finite dimensional quantum systems and prove its attainability in the generic case where the spectrum is non-degenerate. Our results hold under an assumption called local asymptotic…

Quantum Physics · Physics 2019-05-09 Yuxiang Yang , Giulio Chiribella , Masahito Hayashi

Hardy's argument constitutes an elegant proof of quantum nonlocality. In this work, we report an exotic application of Hardy's nonlocal correlations in two-party communication setup. We come up with a task, wherein a positive payoff can be…

We establish a device-independent, noise-tolerant certification of maximally entangled states in every finite dimension $d$. The core ingredient is a $d$-input, $d$-outcome Bell experiment that generalizes the Clauser-Horne-Shimony-Holt…

Quantum Physics · Physics 2025-08-05 Uta Isabella Meyer , Ivan Šupić , Frédéric Grosshans , Damian Markham

Tests such as Bell's inequality and Hardy's paradox show that joint probabilities and correlations between distant particles in quantum mechanics are inconsistent with local realistic theories. Here we experimentally demonstrate these…

Bipartite quantum states with higher Schmidt numbers have been shown to outperform those with lower Schmidt numbers in various quantum information processing tasks, highlighting the operational advantage of entanglement dimensionality.…

Quantum Physics · Physics 2025-12-19 Saheli Mukherjee , Bivas Mallick , Arun Kumar Das , Amit Kundu , Pratik Ghosal

Nonlocal correlations as revealed by the violations to Bell inequalities are incompatible with local models without any nonlocal correlations. However some tripartite entangled states, e.g., symmetric pure states, exhibit a stronger…

Quantum Physics · Physics 2013-06-25 Sixia Yu , C. H. Oh

Nonlocality and quantum entanglement constitute two special aspects of the quantum correlations existing in quantum systems, which are of paramount importance in quantum-information theory. Traditionally, they have been regarded as…

Quantum Physics · Physics 2015-05-27 J. Batle , M. Casas

Bell nonlocality is the key quantum resource in some device-independent quantum information processing. It is of great importance to study the efficient sharing of this resource. Unsharp measurements are widely used in sharing the…

Quantum Physics · Physics 2024-02-21 Tinggui Zhang , Hong Yang , Shao-Ming Fei

We extend the validity of Hardy's nonlocality without inequalities proof to cover the case of special one-parameter classes of non-pure statistical operators. These mixed states are obtained by mixing the Hardy states with a completely…

Quantum Physics · Physics 2009-11-13 GianCarlo Ghirardi , Luca Marinatto

A recent paper [L. Heaney, A. Cabello, M. F. Santos, and V. Vedral, New Journal of Physics, 13, 053054 (2011)] revealed that a single quantum symmetrically delocalized over N modes, namely a W state, effectively allows for…

Quantum Physics · Physics 2012-01-10 Amine Laghaout , Gunnar Björk , Ulrik L. Andersen

Nonlocality can be studied through different approaches, such as Bell's inequalities, and it can be found in numerous quantum states, including GHZ states or graph states. Hardy's paradox, or Hardy-type nonlocality, provides a way to…

Quantum Physics · Physics 2026-01-09 Duc Manh Doan , Hung Q. Nguyen

Recent findings suggest, separable states, which are otherwise of no use in entanglement dependent tasks, can also be used in information processing tasks that depend upon the discord type general non classical correlations. In this work,…

Quantum Physics · Physics 2023-07-12 Ajoy Sen , Debasis Sarkar , Amit Bhar

Bell non-local correlations cannot be naturally explained in a fixed causal structure. This serves as a motivation for considering models where no global assumption is made beyond logical consistency. The assumption of a fixed causal order…

Quantum Physics · Physics 2016-04-06 Ämin Baumeler , Stefan Wolf

We define a property called nondegeneracy for Bell inequalities, which describes the situation that in a Bell setting, if a Bell inequality and involved local measurements are chosen and fixed, any quantum state with a given dimension and…

Quantum Physics · Physics 2021-03-24 Zhaohui Wei , Lijinzhi Lin

We investigate the ability of a quantum measurement device to discriminate two states or, generically, two hypothesis. In full generality, the measurement can be performed a number $n$ of times, and arbitrary pre-processing of the states…

Quantum Physics · Physics 2017-04-26 Christoph Hirche , Masahito Hayashi , Emilio Bagan , John Calsamiglia

Experiments motivated by Bell's theorem have led some physicists to conclude that quantum theory is nonlocal. However, the theoretical basis for such claims is usually taken to be Bell's Theorem, which shows only that if certain predictions…

Quantum Physics · Physics 2007-05-23 Henry P. Stapp

We provide an interesting two-party parity oblivious communication game whose success probability is solely determined by the Bell expression. The parity-oblivious condition in an operational quantum theory implies the preparation…

Quantum Physics · Physics 2021-12-30 A. K. Pan