# On non-linear Schr\"{o}dinger equations for open quantum systems

## TL;DR

This paper explores two generalized nonlinear Schrödinger equations derived from scale relativity theory, analyzing their dissipative and stochastic quantum dynamics through Bohmian mechanics, with applications to uncertainty, diffusion, and tunneling phenomena.

## Contribution

It introduces and analyzes two new nonlinear Schrödinger equations based on scale relativity, extending their application to dissipative and stochastic quantum systems within the Bohmian framework.

## Key findings

- Uncertainty principle is affected by dissipative dynamics.
- Brownian-Bohmian motion shows classical and quantum diffusion behaviors.
- Early arrival phenomena occur in stochastic tunneling despite friction.

## Abstract

Recently two generalized nonlinear Schr\"{o}dinger equations have been proposed by Chavanis [Eur. Phys. J. Plus 132 (2017) 286] by applying Nottale's theory of scale relativity relying on a fractal space-time to describe dissipation in quantum systems. Several existing nonlinear equations are then derived and discussed in this context leading to a continuity equation with an extra source/sink term which violates Ehrenfest theorem. An extension to describe stochastic dynamics is also carried out by including thermal fluctuations or noise of the environment. These two generalized nonlinear equations are analyzed within the Bohmian mechanics framework to describe the corresponding dissipative and stochastic dynamics in terms of quantum trajectories. Several applications of this second generalized equation which can be considered as a generalized Kostin equation have been carried out. The first application consists of the study of the position-momentum uncertainty principle in a dissiaptive dynamics. After, the so-called Brownian-Bohmian motion is investigated by calculating classical and quantum diffusion coefficients. And as a third example, transmission through a transient (time dependent) parabolic repeller is studied where the interesting phenomenon of early arrival is observed even in the stochastic dynamics although the magnitude of early arrival is reduced by friction.