Local exact controllability of the 1D nonlinear Schr\"odinger equation in the case of Dirichlet boundary conditions

TL;DR

This paper proves local exact controllability of the 1D nonlinear Schrödinger equation with Dirichlet boundary conditions using a novel control strategy involving four Fourier modes, extending previous results from Neumann conditions.

Contribution

It introduces a new controllability approach for the Dirichlet case by controlling four specific directions, including Fourier modes, and demonstrates the exact controllability of the nonlinear equation.

Findings

Linearised equation's reachable set is closed.

Control via four directions achieves approximate controllability.

Nonlinear controllability established using inverse mapping theorem.

Abstract

We consider the 1D nonlinear Schr\"odinger equation with bilinear control. In the case of Neumann boundary conditions, local exact controllability of this equation near the ground state has been proved by Beauchard and Laurent in arXiv:1001.3288. In this paper, we study the case of Dirichlet boundary conditions. To establish the controllability of the linearised equation, we use a bilinear control acting through four directions: three Fourier modes and one generic direction. The Fourier modes are appropriately chosen so that they satisfy a saturation property. These modes allow to control approximately the linearised Schr\"odinger equation. We show that the reachable set for the linearised equation is closed. This is achieved by representing the resolving operator as a sum of two linear continuous mappings: one is surjective (here the control in generic direction is used) and the other is compact. A mapping with dense and closed image is surjective, so the linearised Schr\"odinger equation is exactly controllable. Then local exact controllability of the nonlinear equation is derived using the inverse mapping theorem.