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We investigate the violation of Bell-type inequalities for two-qubit Werner-like states parametrized by the positive parameter 0<p<1. We use an unbalanced homodyne detection scheme to obtain the quantum mechanical probabilities. A violation…

Quantum Physics · Physics 2009-11-13 Christoph F. Wildfeuer , Jonathan P. Dowling

We show that bipartite bound entangled states make possible violations of correlation inequalities in the prepare-and-measure scenario. These inequalities are satisfied by all classical models as well as by all quantum models that do not…

Quantum Physics · Physics 2025-03-28 Carles Roch I Carceller , Armin Tavakoli

Last years, bounds on the maximal quantum violation of general Bell inequalities were intensively discussed in the literature via different mathematical tools. In the present paper, we analyze quantum violation of general Bell inequalities…

Quantum Physics · Physics 2019-11-19 Elena R. Loubenets

Contemporary versions of Bell's argument against local hidden variable (LHV) theories are based on the Clauser Horne Shimony and Holt (CHSH) inequality, and various attempts to generalize it. The amount of violation of these inequalities…

Quantum Physics · Physics 2009-11-13 Itamar Pitowsky

In this work we investigate the probability of violation of local realism under random measurements in parallel with the strength of these violations as described by resistance to white noise admixture. We address multisetting Bell…

Quantum Physics · Physics 2020-01-22 Anna de Rosier , Jacek Gruca , Fernando Parisio , Tamas Vertesi , Wieslaw Laskowski

We derive a multipartite generalized Bell inequality which involves the entire range of settings for each of the local observers. Especially, it is applied to show non-local behavior of a six-qubit mixture of Greenberger-Horne-Zeilinger…

Quantum Physics · Physics 2009-11-13 Koji Nagata

We consider properties of states of many qubits, which arise after sending certain entangled states via various noisy channels (white noise, coloured noise, local depolarization, dephasing and amplitude damping). Entanglement of these…

Quantum Physics · Physics 2015-05-13 Wieslaw Laskowski , Tomasz Paterek , Caslav Brukner , Marek Zukowski

We study the relation between distillability of multipartite states and violation of Bell's inequality. We prove that there exist multipartite bound entangled states (i.e. non-separable, non-distillable states) that violate a multipartite…

Quantum Physics · Physics 2009-11-07 W. Dür

At first sight, the use of an everywhere positive Wigner function as a probability density to perform stochastic simulations in quantum optics seems equivalent to the introduction of local hidden variables, thus preventing any violation of…

Quantum Physics · Physics 2021-02-02 Eric Lantz , Mehdi Mabed , Fabrice Devaux

Violation of a Bell inequality guarantees the existence of quantum correlations in a quantum state. A pure bipartite quantum state, having nonvanishing quantum correlation, always violates a Bell inequality. Such correspondence is absent…

Quantum Physics · Physics 2016-07-06 Kunal Sharma , Tamoghna Das , Aditi Sen De , Ujjwal Sen

When separated measurements on entangled quantum systems are performed, the theory predicts correlations that cannot be explained by any classical mechanism: communication is excluded because the signal should travel faster than light;…

Quantum Physics · Physics 2011-08-11 Daniel Cavalcanti , Nicolas Brunner , Paul Skrzypczyk , Alejo Salles , Valerio Scarani

We construct a Bell inequality from the Clauser-Horne-Shimony-Holt inequality for two qubits that provides a stronger bound on the correlations of entangled states than allowed by the CHSH inequality. The argument involved here can be…

Quantum Physics · Physics 2007-11-07 Zeqian Chen

The quantum coherence of a multipartite system is investigated when some of the parties are moving with uniform acceleration and the analysis is carried out using the single mode approximation. Due to acceleration the quantum coherence is…

Lorentz transformation of three-qubit Greenberger-Horne-Zeilinger (GHZ) state is studied. Also we obtain the relativistic spin joint measurement for the transformed state. Using these results it is shown that Bell's inequality is maximally…

Quantum Physics · Physics 2015-06-03 Shahpoor Moradi

We have recently shown that for the special case of a bipartite system with binary inputs and outputs there exist equalities in local theories which are violated by quantum theory. The amount of white noise tolerated by these equalities are…

Quantum Physics · Physics 2008-10-16 Hossein Movahhedian

Inspired the low $\ell$ cosmic variance we present a study on the statistical variance expected in observing Bell's inequality violation by primordial quantum states violation. We consider the statistical variance inherent to three sets of…

Cosmology and Nongalactic Astrophysics · Physics 2020-03-31 Michael J. P. Morse

Bell's Theorem started with two qubits, spins $1/2$. It is a no-go statement on classical (local causal) models of quantum correlations. Only after 25 years, it turned out that for three qubits the situation is even more mind boggling.…

Quantum Physics · Physics 2014-10-16 Wieslaw Laskowski , Junghee Ryu , Marek Zukowski

We report on the experimental violation of multipartite Bell inequalities by entangled states of trapped ions. First we consider resource states for measurement-based quantum computation of between 3 and 7 ions and show that all strongly…

Quantum Physics · Physics 2014-03-19 B. P. Lanyon , M. Zwerger , P. Jurcevic , C. Hempel , W. Dür , H. J. Briegel , R. Blatt , C. F. Roos

The characterization of a quantum system can be complicated by non-ideal measurement processes. In many systems, the underlying physical measurement is only sensitive to a single fixed state, complementary outcomes are inferred by…

Quantum Physics · Physics 2014-12-24 Kaila C. S. Hall , Daniel K. L. Oi

We show that the rich structure of multipartite entanglement can be tested following a device-independent approach. Specifically we present Bell inequalities for distinguishing between different types of multipartite entanglement, without…

Quantum Physics · Physics 2015-05-30 Nicolas Brunner , James Sharam , Tamas Vertesi