The QKP limit of the quantum Euler-Poisson equation

TL;DR

This paper derives different forms of the Kadomtsev-Petviashvili (KP) equation from the quantum Euler-Poisson system, showing how the quantum parameter influences the resulting equation type in the long wavelength limit.

Contribution

It provides a rigorous derivation of the quantum KP equations for the first time, revealing the dependence on the quantum parameter and using anisotropic norms for the proof.

Findings

QKP-I derived for H>2

QKP-II derived for 0<H<2

Dispersive-less KP (dKP) for H=2

Abstract

In this paper, we consider the derivation of the Kadomtsev-Petviashvili (KP) equation for cold ion-acoustic wave in the long wavelength limit of the two-dimensional quantum Euler-Poisson system, under different scalings for varying directions in the Gardner-Morikawa transform. It is shown that the types of the KP equation depend on the scaled quantum parameter $H>0$. The QKP-I is derived for $H>2$, QKP-II for $0<H<2$ and the dispersive-less KP (dKP) equation for the critical case $H=2$. The rigorous proof for these limits is given in the well-prepared initial data case, and the norm that is chosen to close the proof is anisotropic in the two directions, in accordance with the anisotropic structure of the KP equation as well as the Gardner-Morikawa transform. The results can be generalized in several directions.