Stable standing waves for Nonlinear Schrödinger-Poisson system with a doping profile
Mathieu Colin, Tatsuya Watanabe
TL;DR
This work analyzes the nonlinear Schrödinger-Poisson system in $\\mathbb{R}^3$ with a doping profile $\\rho$, aiming to obtain stable standing waves as $L^2$-constraint minimizers of the energy. The authors reduce the coupled system to a single equation via $\\phi = e S(u)$ and decompose the energy into local and nonlocal terms, including $A_1(u)$, $A_2(u)$, and a constant $A_0$, with $S_1(u) \ge 0$. A scaling argument inspired by $\\cite{ZZou}$ is developed to establish strict sub-additivity of the constrained energy even in the presence of $\\rho$, yielding existence of minimizers for large mass when $\\|\\rho\\|_{\frac{6}{5}}$ and $\\|x\\cdot\\nabla\\rho\\|_{\frac{6}{5}}$ are small; this yields orbital stability of standing waves. The paper also treats the case where $\\rho$ is a characteristic function of a bounded domain by leveraging a sharp boundary trace inequality and a small geometric size condition, and proves global well-posedness in the $L^2$-subcritical regime. An open question concerns possible nonexistence of minimizers for large $\\|\\rho\\|_{\frac{6}{5}}$ in 3D.
Abstract
This paper is devoted to the study of the nonlinear Schrödinger-Poisson system with a doping profile. We are interested in the existence of stable standing waves by considering the associated $L^2$-minimization problem. The presence of a doping profile causes a difficulty in the proof of the strict sub-additivity. A key ingredient is to establish the strict sub-additivity by adapting a scaling argument, which is inspired by \cite{ZZou}. When the doping profile is a characteristic function supported on a bounded smooth domain, smallness of some geometric quantity related to the domain ensures the existence of stable standing waves.
