Diffusive limit and Fourier's law for the discrete Schroedinger equation

TL;DR

This paper studies a stochastic perturbation of the discrete Schrödinger equation, demonstrating that it exhibits diffusive behavior described by the heat equation and obeys Fourier's law at the stationary state.

Contribution

It proves the hydrodynamic limit of the stochastic discrete Schrödinger equation and establishes Fourier's law for the stationary state under boundary conditions.

Findings

Hydrodynamic limit given by the heat equation

Stationary state satisfies Fourier's law

System exhibits diffusive behavior in the limit

Abstract

We consider the one-dimensional discrete linear Schrodinger (DLS) equation perturbed by a conservative stochastic dynamics, that changes the phase of each particles, conserving the total norm (or number of particles). The resulting total dynamics is a degenerate hypoelliptic diffusion with a smooth stationary state. We will show that the system has a hydrodynamical limit given by the solution of the heat equation. When it is coupled at the boundaries to two Langevin thermostats at two different chemical potentials, we prove that the stationary state, in the limit as N ! 1, satisfies the Fourier's law.