N. K. Solovarov | Searcharxiv

arXiv2006

Anzatz of quantum correlation and disentanglement problem

Pedagogical introduction into the problem of the mathematical description of the quantum correlation (entanglement) of composite quantum systems is represented. The notion is substantiated about the fact that the conventional algorithm of the reduction of von Neumann in the description of the dynamics of the observed subsyatem is not universal and corresponds only to the case of maximum macroscopicity of the unobservable subsystem. Is clearly shown the sense of the algorithm of the correlated reduction proposed, which minimally changes the entropy of composite system.

quant-ph↗

arXiv2003

Algorithm of Reduction

We show that the von Neumann's algorithm of reduction (i.e. the algorithm of calculating the density matrix of the observable subsystem from the density matrix of the closed quantum system) corresponds to the special approximation at which the unobservable subsystem is supposed to be in the steady state of minimum information (infinite temperature). We formulate the generalized algorithm of reduction that includes as limiting cases the von Neumann's reduction and the self-congruent correlated reduction most corresponding to the quantum nondemolition measurement. We demonstrate the correlation in dynamics of subsystems with exactly soluble models of quantum optics: 1) about the dynamics of a pair of interacting two-level atoms, and 2) about the dynamics of a two-level atom interacting with a single-mode resonant field.

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