Quantum Register and Data Processing, Entanglement, the Bell States, and EPR Paradox

Hiu Yung Wong

Philippe Grangier

Andrei Yu. Khrennikov, Igor Vasil'evich Volovich

There is an opinion that the Bohm reformulation of the EPR paradox in terms of spin variables is equivalent to the original one. In this note we show that such an opinion is not justified. We apply to the original EPR problem the method which was used by Bell for the Bohm reformulation. He has shown that correlation function of two spins cannot be represented by classical correlation of separated bounded random processes. This Bell`s theorem has been interpreted as incompatibility of local realism with quantum mechanics. We show that, in contrast to Bell`s theorem for spin or polarization correlation functions, the correlation of positions (or momenta) of two particles, depending on the rotation angles, in the original EPR model always admits a representation in the form of classical correlation of separated random processes. In this sense there exists a local realistic representation for the original EPR model but there is no such a representation for the Bohm spin reformulation of the EPR paradox. It shows also that the phenomena of quantum nonlocality is based not only on the properties of entangled states but also on the using of particular bounded observables.

Md Anwarul Islam Aion

Aayush Verma

B. C. Sanctuary

Disentanglement refers to decoherence that destroys the quantum interference terms between particles as they separate. This process reduces the pure isotropic entangled EPR state to a mixed anisotropic state. Averaging over the ensemble of states leads to correlations between separated particles that satisfies Bell's inequalities. Applying disentanglement to EPR pairs of photons shows that entanglement is characterized by various two-particle symmetry properties. These symmetry properties are destroyed by disentanglement but photon helicity is conserved. This is sufficient to account for the correlations needed to resolve the EPR paradox. Apart from a numerical factor, the functional form for the correlations due to entanglement and disentanglement is identical, thereby making it difficult to distinguish between the two in the current experiments.