Ali Ahanj

Nonlocality without inequality for almost all two-qubit entangled states based on Cabello's nonlocality argument

Here we deal with a nonlocality argument proposed by Cabello, which is more general than Hardys nonlocality argument, but still maximally entangled states do not respond. However, for most of the other entangled states, maximum probability of success of this argument is more than that of the Hardys argument.

Factorization law for two lower bounds of concurrence

We study the dynamics of two lower bounds of concurrence in bipartite quantum systems when one party goes through an arbitrary channel. We show that these lower bounds obey the factorization law similar to that of [Konrad et al., Nat. Phys. 4, 99 (2008)]. We also, discuss the application of this property, in an example.

Classical simulation of two spin-s singlet state correlations involving spin measurements

Abstract We give a classical protocol to exactly simulate quantum correlations implied by a spin- s singlet state for the infinite sequence of spins satisfying ( 2 s + 1 ) = 2 n , in the worst-case scenario, where n is a positive integer. The class of measurements we consider here are only those corresponding to spin observables. The required amount of communication is found to be log 2 d where d = 2 s + 1 is the dimension of the spin- s Hilbert space.

Downward relativistic potential step and phenomenological account of Bohmian trajectories of the Klein paradox

Abstract.The Dirac equation has been applied to fermions scattering from the downward potential step. The results show that some particles do not fall off the edge of the step and reflect. Then, based on the de Broglie-Bohm interpretation of quantum mechanics (Bohmian mechanics) and Bohmian trajectories we have resolved the problem. Lastly, a phenomenological study of the Bohmian trajectory of the Klein paradox has been discussed.

CLASSICAL PROTOCOL FOR SIMULATION OF SPIN MEASUREMENT CORRELATIONS OF BINARY SPIN-S SINGLET STATE

In a recent paper [A. Ahanj et al., Phys. Lett. A368 (2007) 34], we gave a classical protocol to simulate quantum correlations corresponding to the spin-s singlet state for the infinite sequence of spins satisfying 2s + 1 = 2n. In the present paper, we have generalized this result by giving a classical protocols to exactly simulate quantum correlations implied by the spin-s singlet state corresponding to all integer as well as half-integer spin values s. The class of measurements we consider here are only those corresponding to spin observables, as has been done in the above-mentioned paper. The required amount of communication is found to be ⌈log2(s + 1)⌉ in the worst case scenario, where ⌈x⌉ is the least integer greater than or equal to x.

Quantum Correlations in Successive Spin Measurements

In this paper, we consider a hidden variable theoretical description of successive measurements of non-commuting spin observables on an input spin-s state. Although these spin observables are non-commuting, they act on different states, and so the joint probabilities for the outputs of successive measurements are well-defined. We show that, in this scenario, hidden variable theory (HVT) leads to Bell-type inequalities for the correlation between the outputs of successive measurements. We account for the maximum violation of these inequalities by quantum correlations (i.e. the correlations of successive measurements on a quantum state) by varying the spin value and the number of successive measurements. Our approach can be used to obtain a measure of the deviation of Quantum Mechanics from the theory obeying realism and time-locality, in terms of the amount of classical information needed to be transferred between successive measurements in order to simulate the above-mentioned correlations in successive measurements.