The Classical Mechanics from the Quantum Equation

This work shows that the stochastic generalization of the quantum hydrodynamic analogy (QHA) has its corresponding stochastic Schrödinger equation (SSE) as similarly happens for the deterministic limit. The SSE owns an imaginary random noise that has a finite correlation distance, so that when the physical length of the problem is much smaller than it, the SSE converges to the standard Schrödinger equation comprehending it. The model shows that in non-linear (weakly bounded) systems, the term responsible of the non-local interaction in the SSE may have a finite range of efficacy maintaining its non-local effect on a finite distance. A non-linear SSE that describes the related large-scale classical dynamics is derived. The work also shows that at the edge between the quantum and the classical regime the SSE can lead to the semi-empirical Gross-Pitaevskii equation.