EPR paradox

Einstein, Podolsky and Rosen (EPR) [Einstein 1935] asked the question of whether the quantum mechanical description of physical world is complete, giving the following example. Two-particles are in the quantum state showing strange correlations if one measures the position or momentum of one particle, one can predict with certainty the result of measuring their counterpart for the second particle. Thus, depending on which measurement is chosen for the first particle, the value of either the momentum or position can be predicted with arbitrary precision for the other particle. The later discussion has concerned the interpretation of the EPR paradox and its implications on quantum theory [Bohr 1935], Later, Bohm considered [Bohm 1951] two entangled spin-1/2 particles, which have become the center of attention on this EPR issue their... 

Abstract We consider a possible realization of the position- and momentum-correlated atomic pairs that are confined to adjacent sites of two mutually shifted optical lattices and are entangled via laser-induced dipole-dipole interactions. The Einstein-Podolsky-Rosen (EPR) "paradox" [Einstein 1935] with translational variables is then modified by lattice-diffraction effects. We study a possible mechanism of creating such diatom entangled states by varying the effective mass of the atoms. 

The preceding formalism of SU(2) phase states can be used in a number of problems of quantum physics. As an illustrative example of great importance, consider the so-called Einstein-Podolsky-Rosen (EPR) paradox [73] (see also discussions in Refs. 14, 15, 74, and 75). The EPR paradox touches on the conceptual problems of reality and locality and existence of hidden variables in quantum physics as well as the more technological aspects of quantum cryptography [34]. 

One of the major trends of current research is the study of transmission of information between the atom and photons in the process of emission and absorption. In particular, the conservation of angular momentum provides the transmission of the quantum phase information in the atom-held system. The atomic quantum phase can be constructed as the 57/(2) phase of the angular momentum of the excited atomic state (Section III). It is shown that this phase has very close connection with the EPR paradox and entangled states in general. Via the integrals of motion, it is mapped into the Hilbert space of multipole photons (Section IV.A). This mapping is adequately described by the dual representation of multipole photons, constructed in another study [46] (see also Section IV.B, below). Instead of the quantum number m, corresponding to the... 

Central to the EPR paradox is a thought experiment in which two spins are initially coupled to a state with S = 0 and are then separated to a large distance, at which they can be separately observed. Quantum mechanics appMently predicts that the two spins remain forever coupled, but this conflicts with Einstein s principle of locality or separability , according to which spatially well separated systems must be independent, no matter how strongly they have interacted in the past. It is now widely held that Einstein was wrong and that non-locality follows inevitably from quantum mechanics i.e. that even distant systems are never truly separable. 

During my student days (pre-university, university, PhD), we learned quantum mechanics from the books authored by L. D. Landau and E. M. Lifshitz, A. S. Davydov, D. Bohm, Feynman s course of Lectures on Physics, and from P. A. M. Dirac s Principles . We were exeited with the theories of hidden variables, EPR paradox, decoherence, entanglement, and concerned for a life of immortal Schrodinger s cat - they were in the air at that time Did I understand it Yes - because, due to a conventional wisdom, I used it more than 24 hours a day and every day. I however doubt - doubt together with Feynman who once remarked that Nobody understands it - that I ve actually understood it. I touched and used it throughout the molecular world, which is nowadays inhabited by 21 million molecules, and which I studied as a quantum chemist - in fact, by education, I am a theoretical physicist. 

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