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The Kochen Specker theorem revealed contextuality as a fundamental nonclassical feature of nature. Nonlocality arises as a special case of contextuality, where entangled states shared by space like separated parties exhibit nonlocal…

Quantum Physics · Physics 2026-03-02 Nripendra Majumdar

We re-visit the generation and evolution of (Bell) nonlocality in hybrid scenarios whose dynamics is determined by the Jaynes-Cummings Hamiltonian, a relevant example of which is the atom-cavity system. Previous approaches evaluate the…

Quantum Physics · Physics 2024-10-15 Alexander Bernal , J. Alberto Casas , Jesus M. Moreno

Contextuality is central to both the foundations of quantum theory and to the novel information processing tasks. Although it was recognized before Bell's nonlocality, despite some recent proposals, it still faces a fundamental problem: how…

Quantum Physics · Physics 2014-04-02 A. Grudka , K. Horodecki , M. Horodecki , P. Horodecki , R. Horodecki , P. Joshi , W. Kłobus , A. Wójcik

We experimentally demonstrate the superior discrimination of separated, unentangled two-qubit correlated states using nonlocal measurements, when compared with measurements based on local operations and classical communications. When…

Quantum Physics · Physics 2008-11-26 G. J. Pryde , J. L. O'Brien , A. G. White , Stephen D. Bartlett

Entanglement is a powerful resource for processing quantum information. In this context pure, maximally entangled states have received considerable attention. In the case of bipartite qubit-systems the four orthonormal Bell-states are of…

Quantum Physics · Physics 2015-06-26 I. Jex , G. Alber , S. M. Barnett , A. Delgado

We consider an ontology, in which contextual nonlocal hidden variables are stored as pre-existing possibilities in a repository outside space-time; and in which the context can be chosen ``freely'' (measurement independence) by each agent,…

Quantum Physics · Physics 2026-05-11 Valerio Scarani , Antoine Suarez

Nonlocality lies at the core of quantum mechanics from both a fundamental and applicative point of view. It is typically revealed by a Bell test, that is by violation of a Bell inequality, whose success depends both on the state of the…

Quantum Physics · Physics 2010-10-04 Bruno Bellomo , Rosario Lo Franco , Giuseppe Compagno

In the quantum system, perfect copying is impossible without prior knowledge. But, perfect copying is possible, if it is known that unknown states to be copied is contained by the set of orthogonal states, which is called the copied set.…

Quantum Physics · Physics 2007-05-23 Masaki Owari , Masahito Hayashi

An operational probabilistic theory where all systems are classical, and all pure states of composite systems are entangled, is constructed. The theory is endowed with a rule for composing an arbitrary number of systems, and with a…

Quantum Physics · Physics 2022-01-24 Giacomo Mauro D'Ariano , Marco Erba , Paolo Perinotti

We investigate the entanglement, CHSH nonlocality, fully entangled fraction and symmetric extendibility of two-qubit states that have a single maximally mixed marginal. Within this set of states, the steering ellipsoid formalism has…

Quantum Physics · Physics 2014-09-01 Antony Milne , David Jennings , Sania Jevtic , Terry Rudolph

We use a recently proposed measure of quantum correlations (work deficit), to measure the strength of the nonlocality of an equal mixture of two bipartite, orthogonal, but locally indistinguishable separable states. This gives supporting…

Quantum Physics · Physics 2009-10-19 Aditi Sen De , Ujjwal Sen

Simulating quantum nonlocality and steering requires augmenting pre-shared randomness with non-vanishing communication cost. This prompts the question of how one may provide such an operational characterization for the quantumness of…

Quantum Physics · Physics 2017-03-22 C. Jebaratnam , S. Aravinda , R. Srikanth

Recently, a framework was established to systematically construct novel universal resource states for measurement-based quantum computation using techniques involving finitely correlated states. With these methods, universal states were…

Quantum Physics · Physics 2009-08-04 J. -M. Cai , W. Dür , M. Van den Nest , A. Miyake , H. J. Briegel

We introduce a hierarchy of semidefinite relaxations of the set of quantum correlations in generalised contextuality scenarios. This constitutes a simple and versatile tool for bounding the magnitude of quantum contextuality. To illustrate…

Quantum Physics · Physics 2021-06-07 Armin Tavakoli , Emmanuel Zambrini Cruzeiro , Roope Uola , Alastair A. Abbott

Epistemological consequences of quantum nonlocality (entanglement) are discussed under the assumption of a universally valid Schr\"odinger equation in the absence of hidden variables. This leads inevitably to a {\it many-minds…

Quantum Physics · Physics 2007-05-23 H. D. Zeh

We discuss quantum non-locality and contextuality using the notion of transition sets. This approach provides a way to obtain a direct logical contradiction with locality/non-contextuality in the EPRB gedanken experiment as well as a clear…

Quantum Physics · Physics 2007-11-19 Hans Westman

While all bipartite pure entangled states violate some Bell inequality, the relationship between entanglement and non-locality for mixed quantum states is not well understood. We introduce a simple and efficient algorithmic approach for the…

Quantum Physics · Physics 2009-11-07 Barbara M. Terhal , Andrew C. Doherty , David Schwab

In a recent work [Phys. Rev. Lett. {\bf 98}, 140402 (2007)] we defined ``steering'', a type of quantum nonlocality that is logically distinct from both nonseparability and Bell-nonlocality. In the bipartite setting, it hinges on the…

Quantum Physics · Physics 2007-11-29 S. J. Jones , H. M. Wiseman , A. C. Doherty

Bell nonlocality refers to correlations between two distant, entangled particles that challenge classical notions of local causality. Beyond its foundational significance, nonlocality is crucial for device-independent technologies like…

Choosing four entangled stets to form an orthogonal and complete basis for a two-particle system, we argue that a local hidden variable model should give the probability of each entangled state if the two-particle system is described by a…

Quantum Physics · Physics 2009-11-07 Xiao-Hua Wu , HongShi Zong , Hou-Rong Pang , Fan Wang