Probabilities and correlations in EPR experiments. The EPR-Bohm-Aharonov [1] system of two correlated spin-half particles or qubits observed by spatially separated observers has often been used as an arena in which to probe fundamental questions about quantum theory. Typically there are four different configurations corresponding to four different experiments and one obtains no-go theorems on (...

The Bell theorem for a pair of two-state systems in a singlet state is formulated for the entire range of measurement settings. Typeset using REVTEX 1 The Bell theorem is usually formulated with the help of the Clauser-Horne [1] or the CHSH inequality [2]. These inequalities are satisfied by any local realistic theory and are violated by quantum mechanical predictions. They involve two apparatu...

In D’Ariano in Philosophy of Quantum Information and Entanglement, Cambridge University Press, Cambridge, UK (2010), one of the authors proposed a set of operational postulates to be considered for axiomatizing Quantum Theory. The underlying idea is to derive Quantum Theory as the mathematical representation of a fair operational framework, i.e. a set of rules which allows the experimenter to m...

Abstract At first sight, the use of an everywhere positive Wigner function as a probability density to perform stochastic simulations in quantum optics seems equivalent introduction local hidden variables, thus preventing any violation Bell inequalities. However, because difference between symmetrically and normally ordered operators, some trajectories can imply negative intensities, despite me...

Supplementary EPAPS Document J. B. Brask,1 L. Jiang,2 A. V. Gorshkov,2 V. Vuletic,3 A. S. Sørensen,1 and M. D. Lukin2 1QUANTOP, The Niels Bohr Institute, University of Copenhagen, 2100 Copenhagen Ø, Denmark 2Department of Physics, Harvard University, Cambridge, MA 02138, USA 3Harvard-MIT Center for Ultracold Atoms, Department of Physics, MIT, Cambridge, MA 02139, USA (Dated: September 29, 2009)...

A non-local box is a virtual device that has the following property: given that Alice inputs a bit at her end of the device and that Bob does likewise, it produces two bits, one at Alice’s end and one at Bob’s end, such that the XOR of the outputs is equal to the AND of the inputs. This box, inspired from the CHSH inequality, was first proposed by Popescu and Rohrlich to examine the question: g...

In a recent letter, Jennewein et al. [1] reported an experiment demonstrating entanglement swapping among two pairs (0,1 and 2,3) of down-converted photons. They accomplished this by performing a Bell measurement on photons 1 and 2, and they verified the effect with regular polarization measurements on photons 0 and 3. By selecting data from runs in which 1,2 are measured to be in the Bell stat...

In this paper we present an analog of the Bell’s inequalities violation test for N qubits to be performed in a nuclear magnetic resonance (NMR) quantum computer. This can be used to simulate or predict results for different Bell’s inequalities tests, with distinct configurations and larger number of qubits. To demonstrate our scheme, we implemented a simulation of the violation of Clauser, Horn...

In this paper, we study relativistic bit commitment, which uses timing and location constraints to achieve information theoretic security. Using those constraints, we consider a relativistic bit commitment scheme introduced by Lunghi et al. This protocol was shown secure against classical adversaries as long as the number of rounds performed in the protocol is not too large. In this work, we st...

Kar’s recent proof showing that a maximally entangled state of two spin-1/2 particles gives the largest violation of a Bell inequality is extended to N spin-1/2 particles (N ≥ 3). In particular, it is shown that all the states yielding a direct contradiction with the assumption of local realism do generally consist of a superposition of maximally entangled states. Recently, Kar (see Ref. [1], a...